We have not authorized anyone to provide you with information different from the information contained in or incorporated by reference in this prospectus, any applicable prospectus supplement and any related free writing prospectus that we may authorize to be provided to you. No dealer, salesperson or other person is authorized to give any information or to represent anything not contained or incorporated by reference in this prospectus, any applicable prospectus supplement or any related free writing prospectus that we may authorize to be provided to you. This prospectus is an offer to sell only the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. You should assume that the information in this prospectus, any applicable prospectus supplement or any related free writing prospectus is accurate only as of the date on the front of the document and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus, any applicable prospectus supplement or any related free writing prospectus, or any sale of our securities. Our business, financial condition, results of operations and prospects may have changed since that date.

This prospectus is part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission, or SEC, using a "shelf" registration process. Under this shelf registration process, we may sell common stock, preferred stock, warrants or debt securities in one or more offerings up to a total dollar amount of $100,000,000. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities under this prospectus, we will provide a prospectus supplement that will contain more specific information about the terms of those securities. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. We may also add, update or change in the prospectus supplement (and in any related free writing prospectus that we may authorize to be provided to you) any of the information contained in this prospectus or in the documents that we have incorporated by reference into this prospectus. We urge you to carefully read this prospectus, any applicable prospectus supplement and any related free writing prospectus, together with the information incorporated herein by reference as described under the headings "Where You Can Find More Information" and "Incorporation by Reference" before buying any of the securities being offered.

i

Unless otherwise specified or required by context, references in this prospectus to "S&W Seed" or "S&W" are to S&W Seed Company, a Nevada corporation, and all references to "we," "us" or "our" are to S&W Seed Company and its subsidiaries.

Trademarks, service marks or trade names of any other companies appearing in this prospectus are the property of their respective owners. Use or display by us of trademarks, service marks or trade names owned by others is not intended to and does not imply a relationship between us, and/or endorsement or sponsorship by, the owners of the trademarks, service marks or trade names.

Our functional and reporting currency is the U.S. Dollar. Foreign currency denominated revenues and expenses are translated using average rates of exchange during the reporting period. Foreign currency denominated monetary assets and liabilities are translated at the rate of exchange in effect at the balance sheet date.

Our fiscal year ends on June 30, and accordingly, the term "fiscal 2016" refers to the fiscal year ended June 30, 2016, with corresponding meanings to any other fiscal year reference.

ii

SUMMARY

Founded in 1980 and headquartered in the Central Valley of California, we are a global agricultural company. Grounded in our historical expertise and what we believe is our present leading position in the breeding, production and sale of alfalfa seed, we continue to build towards our goal of being recognized as the world's preferred proprietary forage, grain and specialty crop seed company. In addition to our primary activities in alfalfa seed, we have recently expanded our product portfolio by adding hybrid sorghum and hybrid sunflower seed, which complement our alfalfa seed offerings by allowing us to leverage our infrastructure, research and development expertise and our distribution channels, as we begin to diversify into what we believe are higher margin opportunities. We also continue to conduct our stevia breeding program, having filed two additional patent applications in fiscal 2016.

Following our initial public offering in fiscal year 2010, we expanded certain pre-existing business initiatives and added new ones, including:

• diversifying our production geographically by expanding from solely producing seed in the San Joaquin Valley of California to initially adding production capability in the Imperial Valley of California, then expanding into Australia (primarily South Australia) and, most recently, adding production in other western states and Canada;
• expanding from solely offering non-dormant varieties to now having a full range of both dormant and non-dormant varieties;
• teaming with Forage Genetics International, LLC, a subsidiary of Land O' Lakes, Inc. to develop GMO alfalfa seeds;
• expanding the depth and breadth of our research and development capabilities in order to develop new varieties of both dormant and non-dormant alfalfa seed with traits sought after by our existing and future customers;
• diversifying into complementary proprietary crops by acquiring the assets of a Queensland, Australia company specializing in breeding and licensing of hybrid sorghum and hybrid sunflower seed;
• expanding our distribution channels and customer base, initially through the acquisition of the customer list of a key international customer in the Middle East in July 2011, and thereafter, through certain strategic acquisitions;
• expanding our sales geographically both through the expansion of our product offerings to make available product needed in regions we historically did not cover and through an expansion of our sales and marketing efforts generally; and
• implementing a stevia breeding program to develop new stevia varieties that incorporate the most desirable characteristics of this all-natural, zero calorie sweetener.

We have accomplished these expansion initiatives through a combination of organic growth and strategic acquisitions, foremost among them:

• the acquisition in July 2011 of certain intangible assets, including the customer information, related to the field seed and small grain business of Genetics International, Inc., which had previously operated in the Middle East and North Africa, or MENA, and which began our transition into selling directly to MENA distributors;
• the acquisition of Imperial Valley Seeds, Inc. in October 2012, which enabled us to expand production of non-GMO seed into California's Imperial Valley, thereby ensuring a non-GMO source of seed due to the prohibition on GMO crops in the Imperial Valley, as well as enabling us to diversify our production areas and distribution channels;
• the acquisition of a portfolio of dormant alfalfa seed germplasm in August 2012 to launch our entry into the dormant market;
• the acquisition of the leading local producer of non-dormant alfalfa seed in South Australia, Seed Genetics International Pty Ltd, or SGI, in April 2013, which greatly expanded our production capabilities and geographic diversity;

1

• the acquisition of the alfalfa production and research facility assets and conventional (non-GMO) alfalfa germplasm from DuPont Pioneer, a wholly-owned subsidiary of E.I. du Pont de Nemours and Company, or DuPont Pioneer, in December 2014, thereby substantially expanding upon our initial entrance into the dormant alfalfa seed market that began in 2012 and enabling us to greatly expand our production and research and product development capabilities; and
• the acquisition, in May 2016, of the assets and business of SV Genetics Pty Ltd, or SV Genetics, a private Australian company specializing in the breeding and licensing of proprietary hybrid sorghum and sunflower seed germplasm, which represents our initial effort to diversify our product portfolio beyond alfalfa seed breeding and production and stevia R&D.

We believe our 2013 combination with SGI created the world's largest non-dormant alfalfa seed company and gave us the competitive advantages of year-round production in that market. With the completion of the acquisition of dormant alfalfa seed assets from DuPont Pioneer in December 2014, we believe we have become the largest alfalfa seed company worldwide (by volume), with industry-leading research and development, as well as production and distribution capabilities in both hemispheres and the ability to supply proprietary dormant and non-dormant alfalfa seed. Our operations span the world's alfalfa seed production regions, with operations in the San Joaquin and Imperial Valleys of California, five additional Western states, Australia and three provinces in Canada.

Our May 2016 acquisition of the hybrid sorghum and sunflower germplasm business and assets of SV Genetics sets us on the road to begin to diversify into product offerings with historically higher margins, and signals management's commitment to our strategy of identifying opportunities to diversify our product lines and improve our gross margins.

We also own and operate seed-cleaning and processing facilities in Five Points, California and Nampa, Idaho and a seed processing facility in Keith, South Australia.

From 1980 until 2009, our business was operated as a general partnership. We bought out the former partners beginning in June 2008, incorporated in Delaware in October 2009 and completed the buyout of the general partners in May 2010. We reincorporated in Nevada in December 2011. SGI, which is our wholly owned subsidiary, was incorporated as a limited proprietary corporation in South Australia in 1993, originally named Harkness Group. It then changed its name to Seed Genetics Australia Pty Ltd in 2002 and changed its name to Seed Genetics International Pty Ltd in 2011.

Our principal business office is located at 7108 North Fresno Avenue, Suite 380, Fresno, CA 93720, and our telephone is number (559) 884-2535. SGI's principal office space is located in Unley, South Australia. Our website address is www.swseedco.com. The information contained in or accessible through our website does not constitute part of this prospectus.

An investment in our securities involves risks. Prior to making a decision about investing in our securities, you should carefully consider the specific risks discussed under "Risk Factors" in any applicable prospectus supplement and in our filings with the SEC incorporated by reference in this prospectus, together with all of the other information contained in this prospectus and any applicable prospectus supplement or incorporated by reference in this prospectus. The risks and uncertainties described in any applicable prospectus supplement and in our SEC filings are not the only ones facing us. Additional risks and uncertainties not presently known to us, or that we currently see as immaterial, may also harm our business. If any of the risks or uncertainties described in any applicable prospectus supplement or our SEC filings or any such additional risks and uncertainties actually occur, our business, results of operations and financial condition could be materially and adversely affected. In that case, the market value and/or trading price, as applicable, of our securities could decline, and you might lose all or part of your investment.

This prospectus and any applicable prospectus supplement or free writing prospectus, including the documents that we incorporate by reference herein and therein, contain "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. These forward-looking statements can generally be identified as such because the context of the statement will include words such as "may," "will," "intend," "plan," "believe," "anticipate," "expect," "estimate," "predict," "potential," "continue," "likely," or "opportunity," the negative of these words or words of similar import. Similarly, statements that describe our future plans, strategies, intentions, expectations, objectives, goals or prospects are also forward-looking statements. Discussions containing these forward-looking statements may be found, among other places, in the "Business" and

2

"Management's Discussion and Analysis of Financial Condition and Results of Operations" sections incorporated by reference from our most recent Annual Report on Form 10-K and our Quarterly Reports on Form 10-Q for the quarterly periods ended subsequent to our filing of such Annual Report on Form 10-K, as well as any amendments thereto reflected in subsequent filings with the SEC. These forward-looking statements are based largely on our expectations and projections about future events and future trends affecting our business, and are subject to risks and uncertainties that could cause actual results to differ materially from those anticipated in the forward-looking statements. The risks and uncertainties include, among others, those noted in "Risk Factors" above and in any applicable prospectus supplement or free writing prospectus, and those included in the documents that we incorporate by reference herein and therein.

In addition, past financial and/or operating performance is not necessarily a reliable indicator of future performance, and you should not use our historical performance to anticipate results or future period trends. We can give no assurances that any of the events anticipated by the forward-looking statements will occur or, if any of them do, what impact they will have on our results of operations and financial condition. Except as required by law, we undertake no obligation to publicly revise our forward-looking statements to reflect events or circumstances that arise after the filing of this prospectus or any applicable prospectus supplement or free writing prospectus, or documents incorporated by reference herein and therein, that include forward-looking statements.

We may offer and sell shares of our common stock and/or preferred stock, various series of debt securities and/or warrants to purchase any of these securities, either individually or in combination with other securities, with a total value of up to $100,000,000, from time to time under this prospectus at prices and on terms to be determined by market conditions at the time of offering. We may also offer common stock or preferred stock upon conversion of debt securities, common stock upon conversion of preferred stock, or common stock, preferred stock or debt securities upon the exercise of warrants. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

• designation or classification;
• aggregate principal amount or aggregate offering price;
• maturity;
• original issue discount;
• rates and times of payment of interest, dividends or other payments;
• redemption, conversion, exercise, exchange or sinking fund terms;
• ranking;
• restrictive covenants;
• voting or other rights; and
• conversion or exchange prices or rates, if any, and, if applicable, any provisions for changes to or adjustments in the conversion or exchange prices or rates and in the securities or other property receivable upon conversion or exchange.

A prospectus supplement and any related free writing prospectus that we may authorize to be provided to you also may add, update or change information contained in this prospectus or in documents we have incorporated by reference. However, no prospectus supplement or free writing prospectus will offer a security that is not registered and described in this prospectus at the time of the effectiveness of the registration statement of which this prospectus is a part.

We may sell the securities directly to investors or to or through agents, underwriters or dealers. We, and our agents or underwriters, reserve the right to accept or reject all or part of any proposed purchase of securities. If we do offer securities through agents or underwriters, we will include in the applicable prospectus supplement:

• the name of those agents or underwriters;
• applicable fees, discounts and commissions to be paid to them;
• details regarding over-allotment options, if any; and
• the net proceeds to us.

3

Common Stock. We may issue shares of our common stock from time to time. Holders of our common stock are entitled to one vote per share on all matters submitted to a vote of stockholders. Subject to any preferences of any of our preferred stock that may be outstanding, holders of our common stock are entitled to dividends when and if declared by our board of directors. Subject to any preferential rights of any outstanding preferred stock, in the event of our liquidation, dissolution or winding up, holders of our common stock are entitled to share ratably in the assets remaining after payment of liabilities and the liquidation preferences of any outstanding preferred stock. Our common stock does not carry any preemptive rights enabling a holder to subscribe for, or receive shares of, any class of our common stock or any other securities convertible into shares of any class of our common stock, or any redemption rights.

Preferred Stock. We may issue shares of our preferred stock from time to time, in one or more series. Our board of directors will determine the designations, voting powers, preferences and rights of the preferred stock, as well as the qualifications, limitations or restrictions thereof, including dividend rights, conversion rights, preemptive rights, terms of redemption or repurchase, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of any series. Convertible preferred stock will be convertible into our common stock or exchangeable for other securities. Conversion may be mandatory or at your option and would be at prescribed conversion rates.

If we sell any series of preferred stock under this prospectus, we will fix the designations, voting powers, preferences and rights of such series of preferred stock, as well as the qualifications, limitations or restrictions thereof, in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that describes the terms of the series of preferred stock that we are offering before the issuance of the related series of preferred stock. We urge you to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the series of preferred stock being offered, as well as the complete certificate of designation that contains the terms of the applicable series of preferred stock.

Warrants. We may issue warrants for the purchase of common stock, preferred stock and/or debt securities in one or more series, from time to time. We may issue warrants independently or together with common stock, preferred stock and/or debt securities, and the warrants may be attached to or separate from these securities. In this prospectus, we have summarized certain general features of the warrants. We urge you, however, to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the particular series of warrants being offered, as well as the complete warrant agreements and warrant certificates that contain the terms of the warrants. Forms of the warrant agreements and forms of warrant certificates containing the terms of the warrants being offered have been filed as exhibits to the registration statement of which this prospectus is a part, and supplemental warrant agreements and forms of warrant certificates will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

We will evidence each series of warrants by warrant certificates that we will issue. Warrants may be issued under an applicable warrant agreement that we enter into with a warrant agent. We will indicate the name and address of the warrant agent, if applicable, in the prospectus supplement relating to the particular series of warrants being offered.

Debt Securities. We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. The senior debt securities will rank equally with any other unsecured and unsubordinated debt. The subordinated debt securities will be subordinate and junior in right of payment, to the extent and in the manner described in the instrument governing the debt, to all of our senior indebtedness. Convertible debt securities will be convertible into or exchangeable for our common stock or other securities. Conversion may be mandatory or at your option and would be at prescribed conversion rates.

The debt securities will or may be issued under one or more documents called indentures, which are contracts between us and a national banking association or other eligible party, as trustee. In this prospectus, we have summarized certain general features of the debt securities. We urge you, however, to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the series of debt securities being offered, as well as the complete indentures that contain the terms of the debt securities. A form of indenture has been filed as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

4

USE OF PROCEEDS

Except as described in any prospectus supplement, we currently intend to use the net proceeds from the sale of securities under this prospectus for general corporate purposes, including for research and development, sales and marketing initiatives and general administrative expenses, working capital and capital expenditures. In addition, we may use a portion of the net proceeds for the repayment of debt or refinancing of indebtedness or the acquisition of land, facilities, property or complementary products or companies, although we have no current plans, commitments or agreements to do so as of the date of this prospectus. The timing and amount of our actual expenditures will be based on many factors, including our future revenue growth, if any, future capital expenditures and the amount of cash required by our operations. We will retain broad discretion in determining how we will allocate the net proceeds from the sale of securities under this prospectus.

As of the date of this prospectus, our articles of incorporation authorizes us to issue 50,000,000 shares of common stock, par value $0.001 per share, and 5,000,000 shares of preferred stock, par value $0.001 per share. As of January 10, 2017, there were 17,963,501 shares of our common stock outstanding and no shares of preferred stock outstanding.

The following summary describes the material terms of our capital stock. The description of our capital stock is qualified by reference to our articles of incorporation and our second amended and restated bylaws, which are incorporated by reference as exhibits into the registration statement of which this prospectus is a part.

Holders of our common stock are entitled to one vote for each share held on all matters submitted to a vote of stockholders. Subject to the preference in dividend rights of any series of preferred stock that we may issue in the future, the holders of common stock are entitled to receive such cash dividends, if any, as may be declared by our board of directors out of legally available funds. Upon liquidation, dissolution or winding up, after payment of all debts and liabilities and after payment of the liquidation preferences of any shares of preferred stock then outstanding, the holders of the common stock will be entitled to participate pro rata in all assets that are legally available for distribution.

Other than the rights described above, the holders of common stock have no preemptive subscription, redemption, sinking fund or conversion rights and are not subject to further calls or assessments. The rights and preferences of holders of common stock will be subject to the rights of any series of preferred stock that we may issue in the future.

We have never had any shares of preferred stock outstanding. Our board of directors, without any further vote or action by our stockholders, has the authority to issue up to an aggregate of 5,000,000 shares of preferred stock from time to time, in one or more classes or series or shares, on terms that it may determine, including among other things:

• its dividend rate;
• its liquidation preference;
• whether or not the shares will be convertible into, or exchangeable for, any other securities; and
• whether or not the shares will have voting rights, and, if so, determine the extent of the voting powers and the conditions under which the shares will vote as a separate class.

We believe that our board of directors' ability to issue preferred stock on such a wide variety of terms will enable the preferred stock to be used for important corporate purposes, such as financing acquisitions or raising additional capital. However, were it inclined to do so, our board of directors could issue all or part of the preferred stock with, among other things, substantial voting power or advantageous conversion rights. This stock could be issued to persons deemed by our board of directors likely to support our current management in a context for control of us, either as a precautionary measure or in response to a specific takeover threat. We have no current plans to issue preferred stock for any purpose.

The issuance of preferred stock could adversely affect the voting power of holders of common stock and reduce the likelihood that common stockholders will receive dividend payments and payments upon liquidation. The issuance could have the effect of decreasing the market price of the common stock. The issuance of preferred stock also could have the effect of delaying, deterring or preventing a change in control.

5

Anti-Takeover Provisions of Nevada Law and Charter Documents

Certain provisions of the Nevada Revised Statutes, as described below, may delay or discourage transactions involving an actual or potential change in our control or change in our management, including transactions in which stockholders might otherwise receive a premium for their shares or transactions that our stockholders might otherwise deem to be in their best interests.

We are subject to Section 78.438 of the Nevada Revised Statutes, an anti-takeover law. In general, Section 78.438 prohibits a Nevada corporation from engaging in any business combination with any interested stockholder for a period of three years following the date that the stockholder became an interested stockholder, unless prior to that date, the board of directors of the corporation approved either the business combination or the transaction that resulted in the stockholder becoming an interested stockholder. Section 78.439 provides that business combinations after the three year period following the date that the stockholder becomes an interested stockholder may also be prohibited unless approved by the corporation's directors or other stockholders or unless the price and terms of the transaction meet the criteria set forth in the statute.

Section 78.416 of the Nevada Revised Statutes defines "business combination" to include the following:

• any merger or consolidation involving the corporation and the interested stockholder or any other corporation which is an affiliate or associate of the interested stockholder;
• any sale, transfer, pledge or other disposition of the assets of the corporation involving the interested stockholder or any affiliate or associate of the interested stockholder if the assets transferred have a market value equal to 5% or more of all of the assets of the corporation or 5% or more of the value of the outstanding shares of the corporation or represent 10% or more of the earning power of the corporation;
• subject to certain exceptions, any transaction that results in the issuance or transfer by the corporation of any stock of the corporation with a market value of 5% or more of the value of the outstanding shares of the corporation;
• the adoption of a plan of liquidation proposed by or under any arrangement with the interested stockholder or any affiliate or associate of the interested stockholder;
• any transaction involving the corporation that has the effect of increasing the proportionate share of the stock of any class or series of the corporation beneficially owned by the interested stockholder or any affiliate or associate of the interested stockholder; or
• the receipt by the interested stockholder or any affiliate or associate of the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other financial benefits provided by or through the corporation.

In general, Section 78.423 of the Nevada Revised Statutes defines an interested stockholder as any entity or person beneficially owning, directly or indirectly, 10% or more of the outstanding voting stock of the corporation and any entity or person affiliated with or controlling or controlled by any of these entities or persons.

The Nevada Revised Statutes contain a provision governing "Acquisition of Controlling Interest," or the control share acquisition act. This law provides generally that any person or entity that acquires 20% or more of the outstanding voting shares of a publicly-held Nevada corporation in the secondary public or private market may be denied voting rights with respect to the acquired shares, unless a majority of the disinterested stockholders of the corporation elects to restore such voting rights in whole or in part. The control share acquisition act provides that a person or entity acquires "control shares" whenever it acquires shares that, but for the operation of the control share acquisition act, would bring its voting power within any of the following three ranges: (a) 20% to 33 1/3%, (b) 33 1/3% to 50%, or (c) more than 50%. A "control share acquisition" is generally defined as the direct or indirect acquisition of either ownership or voting power associated with issued and outstanding control shares. The stockholders or board of directors of a corporation may elect to exempt the stock of the corporation from the provisions of the control share acquisition act through adoption of a provision to that effect in the Articles of Incorporation or Bylaws of the corporation. The control share acquisition act is applicable only to shares of "Issuing Corporations" as defined by the act. An Issuing Corporation is a Nevada corporation, which; (i) has 200 or more stockholders of record, with at least 100 of such stockholders being both stockholders of record and residents of Nevada; and (ii) does business in Nevada directly or through an affiliated corporation. At this time, we do not have 200 stockholders of record or 100 stockholders of record resident of Nevada.  If the control share acquisition act becomes applicable to us, its application may discourage companies or persons interested in acquiring a significant interest in or control of us, regardless of whether such acquisition may be in the interest of our stockholders.

6

Articles of Incorporation and Bylaw Provisions.

Our articles of incorporation and bylaws contain provisions that might have an anti-takeover effect. These provisions, which are summarized below, may have the effect of delaying, deterring or preventing a change in control of our company. They could also impede a transaction in which our stockholders might receive a premium over the then-current market price of our common stock and our stockholders' ability to approve transactions that they consider to be in their best interests.

Articles of Incorporation. Our authorized but unissued shares of common stock and preferred stock are available for our board of directors to issue without stockholder approval. We may use these additional shares for a variety of corporate purposes, including future public or private offerings to raise additional capital, corporate acquisitions and employee benefit plans. The existence of our authorized but unissued shares of common stock and preferred stock could render more difficult or discourage an attempt to obtain control of our company by means of a proxy contest, tender offer, merger or other transaction. Our authorized but unissued shares may be used to delay, defer or prevent a tender offer or takeover attempt that a stockholder might consider in its best interest, including those attempts that might result in a premium over the market price for the shares held by our stockholders.

Bylaws. Certain provisions of our bylaws may be considered to have anti-takeover effects, including advance notice requirements for director nominations and other stockholder proposals. Our bylaws establish advance notice procedures for stockholder proposals to be brought before an annual meeting of stockholders, and for proposed nominations of candidates for election to our board of directors at an annual or special meeting of stockholders. Generally, such notices must be received by our corporate secretary, in the case of an annual meeting, between 90 days and 120 days prior to the first anniversary of the preceding year's annual meeting and, in the case of a special meeting called for the purpose of electing directors, between 90 and 120 days prior to the date of the special meeting or within 10 days after the day on which public announcement of the date of the special meeting is first made by us. In addition, the exclusive authority to adopt, amend or repeal our bylaws is vested with our board of directors, which could delay, deter or prevent a change of control.

The transfer agent and registrar for our common stock is Transfer Online, Inc.

Our common stock is listed on the NASDAQ Capital Market under the symbol "SANW."

We may issue warrants from time to time under this prospectus for the purchase of common stock, preferred stock and/or debt securities in one or more series. We may issue warrants independently or together with common stock, preferred stock and/or debt securities, and the warrants may be attached to or separate from these securities. While the terms summarized below will apply generally to any warrants that we may offer, we will describe the particular terms of any series of warrants in more detail in the applicable prospectus supplement. The terms of any warrants offered under a prospectus supplement may differ from the terms described below.

Warrants issued under this prospectus may be issued under warrant agreements, which we will enter into with a warrant agent to be selected by us. We use the term "warrant agreement" to refer to any of these warrant agreements. We use the term "warrant agent" to refer to the warrant agent under any of these warrant agreements. Any warrant agent will act solely as an agent of ours in connection with the warrants and will not act as an agent for the holders or beneficial owners of the warrants.

We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of warrant agreement, including a form of warrant certificate, that describes the terms of the particular series of warrants we are offering before the issuance of the related series of warrants. The following summaries of material provisions of the warrants and the warrant agreements are subject to, and qualified in their entirety by reference to, all the provisions of the warrant agreement and warrant certificate applicable to the particular series of warrants that we may offer under this prospectus. We urge you to read the applicable prospectus supplements and any free writing prospectus related to the particular series of warrants that we offer under this prospectus, as well as the complete warrant agreements and warrant certificates that contain the terms of the warrants.

7

General

We will describe in the applicable prospectus supplement the terms of the series of warrants being offered, including, to the extent applicable:

• the offering price and aggregate number of warrants offered;
• the currency for which the warrants may be purchased;
• the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each such security or each principal amount of such security;
• the date on and after which the warrants and the related securities will be separately transferable;
• in the case of warrants to purchase debt securities, the principal amount of debt securities purchasable upon exercise of one warrant and the price at, and currency in which, this principal amount of debt securities may be purchased upon such exercise;
• in the case of warrants to purchase common stock or preferred stock, the number of shares of common stock or preferred stock, as the case may be, purchasable upon the exercise of one warrant and the price at which these shares may be purchased upon such exercise;
• the effect of any merger, consolidation, sale or other disposition of our business on the warrant agreements and the warrants;
• the terms of any rights to redeem or call the warrants;
• any provisions for changes to or adjustments in the exercise price or number of securities issuable upon exercise of the warrants;
• the dates on which the right to exercise the warrants will commence and expire;
• the manner in which the warrant agreements and warrants may be modified;
• a discussion of material U.S. federal income tax consequences of holding or exercising the warrants;
• the terms of the securities issuable upon exercise of the warrants; and
• any other specific terms, preferences, rights or limitations of or restrictions on the warrants.

Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:

• in the case of warrants to purchase debt securities, the right to receive payments of principal of, or premium, if any, or interest on, the debt securities purchasable upon exercise or to enforce covenants in the applicable indenture; or
• in the case of warrants to purchase common stock or preferred stock, the right to receive dividends, if any, or, payments upon our liquidation, dissolution or winding up or to exercise voting rights, if any.

Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to the specified time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

Holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information, and paying the required amount to the warrant agent, if applicable, in immediately available funds, as provided in the applicable prospectus supplement. We will set forth on the reverse side of the warrant certificate and in the applicable prospectus supplement the information that the holder of the warrant will be required to deliver to the warrant agent.

Upon receipt of the required payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the securities purchasable upon such exercise. If fewer than all of the warrants represented by the warrant certificate are exercised, then we will issue a new warrant certificate for the remaining amount of warrants. If we so indicate in the applicable prospectus supplement, holders of the warrants may surrender securities as all or part of the exercise price for warrants.

Unless we provide otherwise in the applicable prospectus supplement, the warrants and warrant agreements will be governed by and construed in accordance with the laws of the State of New York.

8

Enforceability of Rights by Holders of Warrants

Any warrant agent will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

We may issue debt securities from time to time under this prospectus, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. While the terms we have summarized below will apply generally to any debt securities that we may offer under this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. The terms of any debt securities offered under a prospectus supplement may differ from the terms described below. Unless the context requires otherwise, whenever we refer to the indenture, we also are referring to any supplemental indentures that specify the terms of a particular series of debt securities.

We will issue the debt securities under the indenture that we will enter into with the trustee named in the indenture. The indenture will be qualified under the Trust Indenture Act of 1939, as amended, or the Trust Indenture Act. We have filed the form of indenture as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

The following summary of material provisions of the debt securities and the indenture is subject to, and qualified in its entirety by reference to, all of the provisions of the indenture applicable to a particular series of debt securities. We urge you to read the applicable prospectus supplements and any related free writing prospectuses related to the debt securities that we may offer under this prospectus, as well as the complete indenture that contains the terms of the debt securities.

The indenture does not limit the amount of debt securities that we may issue. It provides that we may issue debt securities up to the principal amount that we may authorize and may be in any currency or currency unit that we may designate. Except for the limitations on consolidation, merger and sale of all or substantially all of our assets contained in the indenture, the terms of the indenture do not contain any covenants or other provisions designed to give holders of any debt securities protection against changes in our operations, financial condition or transactions involving us.

We may issue the debt securities issued under the indenture as "discount securities," which means they may be sold at a discount below their stated principal amount. These debt securities, as well as other debt securities that are not issued at a discount, may be issued with "original issue discount," or OID, for U.S. federal income tax purposes because of interest payment and other characteristics or terms of the debt securities. Material U.S. federal income tax considerations applicable to debt securities issued with OID will be described in more detail in any applicable prospectus supplement.

We will describe in the applicable prospectus supplement the terms of the series of debt securities being offered, including:

• the title of the series of debt securities;
• any limit upon the aggregate principal amount that may be issued;
• the maturity date or dates;
• the form of the debt securities of the series;
• the applicability of any guarantees;
• whether or not the debt securities will be secured or unsecured, and the terms of any secured debt;
• whether the debt securities rank as senior debt, senior subordinated debt, subordinated debt or any combination thereof, and the terms of any subordination;
• if the price (expressed as a percentage of the aggregate principal amount thereof) at which such debt securities will be issued is a price other than the principal amount thereof, the portion of the principal amount thereof payable upon declaration of acceleration of the maturity thereof, or if applicable, the portion of the principal amount of such debt securities that is convertible into another security or the method by which any such portion shall be determined;

9

• the interest rate or rates, which may be fixed or variable, or the method for determining the rate and the date interest will begin to accrue, the dates interest will be payable and the regular record dates for interest payment dates or the method for determining such dates;
• our right, if any, to defer payment of interest and the maximum length of any such deferral period;
• if applicable, the date or dates after which, or the period or periods during which, and the price or prices at which, we may, at our option, redeem the series of debt securities pursuant to any optional or provisional redemption provisions and the terms of those redemption provisions;
• the date or dates, if any, on which, and the price or prices at which we are obligated, pursuant to any mandatory sinking fund or analogous fund provisions or otherwise, to redeem, or at the holder's option to purchase, the series of debt securities and the currency or currency unit in which the debt securities are payable;
• the denominations in which we will issue the series of debt securities, if other than denominations of $1,000 and any integral multiple thereof;
• any and all terms, if applicable, relating to any auction or remarketing of the debt securities of that series and any security for our obligations with respect to such debt securities and any other terms which may be advisable in connection with the marketing of debt securities of that series;
• whether the debt securities of the series shall be issued in whole or in part in the form of a global security or securities; the terms and conditions, if any, upon which such global security or securities may be exchanged in whole or in part for other individual securities; and the depositary for such global security or securities;
• if applicable, the provisions relating to conversion or exchange of any debt securities of the series and the terms and conditions upon which such debt securities will be so convertible or exchangeable, including the conversion or exchange price, as applicable, or how it will be calculated and may be adjusted, any mandatory or optional (at our or the holders' option) conversion or exchange features, the applicable conversion or exchange period and the manner of settlement for any conversion or exchange;
• if other than the full principal amount thereof, the portion of the principal amount of debt securities of the series which shall be payable upon declaration of acceleration of the maturity thereof;
• additions to or changes in the covenants applicable to the particular debt securities being issued, including, among others, the consolidation, merger or sale covenant;
• additions to or changes in the events of default with respect to the securities and any change in the right of the trustee or the holders to declare the principal, premium, if any, and interest, if any, with respect to such securities to be due and payable;
• additions to or changes in or deletions of the provisions relating to covenant defeasance and legal defeasance;
• additions to or changes in the provisions relating to satisfaction and discharge of the indenture;
• additions to or changes in the provisions relating to the modification of the indenture both with and without the consent of holders of debt securities issued under the indenture;
• the currency of payment of debt securities if other than U.S. dollars and the manner of determining the equivalent amount in U.S. dollars;
• whether interest will be payable in cash or additional debt securities at our or the holders' option and the terms and conditions upon which the election may be made;
• the terms and conditions, if any, upon which we will pay amounts in addition to the stated interest, premium, if any and principal amounts of the debt securities of the series to any holder that is not a "United States person" for federal tax purposes;
• any restrictions on transfer, sale or assignment of the debt securities of the series; and
• any other specific terms, preferences, rights or limitations of, or restrictions on, the debt securities, any other additions or changes in the provisions of the indenture, and any terms that may be required by us or advisable under applicable laws or regulations.

We will set forth in the applicable prospectus supplement the terms on which a series of debt securities may be convertible into or exchangeable for our common stock or our other securities. We will include provisions as to settlement upon conversion or exchange and whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock or our other securities that the holders of the series of debt securities receive would be subject to adjustment.

10

Consolidation, Merger or Sale

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the indenture will not contain any covenant that restricts our ability to consolidate or merge, or sell, convey, transfer or otherwise dispose of our assets as an entirety or substantially as an entirety. However, any successor to or acquirer of such assets (other than a subsidiary of ours) must assume all of our obligations under the indenture or the debt securities, as appropriate.

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the following are events of default under the indenture with respect to any series of debt securities that we may issue:

• if we fail to pay any installment of interest on any series of debt securities, as and when the same shall become due and payable, and such default continues for a period of 90 days; provided, however, that a valid extension of an interest payment period by us in accordance with the terms of any indenture supplemental thereto shall not constitute a default in the payment of interest for this purpose;
• if we fail to pay the principal of, or premium, if any, on any series of debt securities as and when the same shall become due and payable whether at maturity, upon redemption, by declaration or otherwise, or in any payment required by any sinking or analogous fund established with respect to such series; provided, however, that a valid extension of the maturity of such debt securities in accordance with the terms of any indenture supplemental thereto shall not constitute a default in the payment of principal or premium, if any;
• if we fail to observe or perform any other covenant or agreement contained in the debt securities or the indenture, other than a covenant specifically relating to another series of debt securities, and our failure continues for 90 days after we receive written notice of such failure, requiring the same to be remedied and stating that such is a notice of default thereunder, from the trustee or holders of at least 25% in aggregate principal amount of the outstanding debt securities of the applicable series; and
• if specified events of bankruptcy, insolvency or reorganization occur.

If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the trustee if notice is given by such holders, may declare the unpaid principal of, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default specified in the last bullet point above occurs with respect to us, the principal amount of and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the trustee or any holder.

The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the indenture. Any waiver shall cure the default or event of default.

Subject to the terms of the indenture, if an event of default under an indenture shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the trustee reasonable indemnity. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or power conferred on the trustee, with respect to the debt securities of that series, provided that:

• the direction so given by the holder is not in conflict with any law or the applicable indenture; and
• subject to its duties under the Trust Indenture Act, the trustee need not take any action that might involve it in personal liability or might be unduly prejudicial to the holders not involved in the proceeding.

A holder of the debt securities of any series will have the right to institute a proceeding under the indenture or to appoint a receiver or trustee, or to seek other remedies only if:

• the holder has given written notice to the trustee of a continuing event of default with respect to that series;
• the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series have made written request;

11

• such holders have offered to the trustee indemnity satisfactory to it against the costs, expenses and liabilities to be incurred by the trustee in compliance with the request; and
• the trustee does not institute the proceeding, and does not receive from the holders of a majority in aggregate principal amount of the outstanding debt securities of that series other conflicting directions within 90 days after the notice, request and offer.

These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

We will periodically file statements with the trustee regarding our compliance with specified covenants in the indenture.

We and the trustee may change an indenture without the consent of any holders with respect to specific matters:

• to cure any ambiguity, defect or inconsistency in the indenture or in the debt securities of any series;
• to comply with the provisions described above under "Description of Debt Securities-Consolidation, Merger or Sale;"
• to provide for uncertificated debt securities in addition to or in place of certificated debt securities;
• to add to our covenants, restrictions, conditions or provisions such new covenants, restrictions, conditions or provisions for the benefit of the holders of all or any series of debt securities, to make the occurrence, or the occurrence and the continuance, of a default in any such additional covenants, restrictions, conditions or provisions an event of default or to surrender any right or power conferred upon us in the indenture;
• to add to, delete from or revise the conditions, limitations, and restrictions on the authorized amount, terms, or purposes of issue, authentication and delivery of debt securities, as set forth in the indenture;
• to make any change that does not adversely affect the interests of any holder of debt securities of any series in any material respect;
• to provide for the issuance of and establish the form and terms and conditions of the debt securities of any series as provided above under "Description of Debt Securities-General" to establish the form of any certifications required to be furnished pursuant to the terms of the indenture or any series of debt securities, or to add to the rights of the holders of any series of debt securities;
• to evidence and provide for the acceptance of appointment under any indenture by a successor trustee; or
• to comply with any requirements of the SEC in connection with the qualification of any indenture under the Trust Indenture Act.

In addition, under the indenture, the rights of holders of a series of debt securities may be changed by us and the trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series that is affected. However, unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, we and the trustee may make the following changes only with the consent of each holder of any outstanding debt securities affected:

• extending the fixed maturity of any debt securities of any series;
• reducing the principal amount, reducing the rate of or extending the time of payment of interest, or reducing any premium payable upon the redemption of any series of any debt securities; or
• reducing the percentage of debt securities, the holders of which are required to consent to any amendment, supplement, modification or waiver.

The indenture provides that we can elect to be discharged from our obligations with respect to one or more series of debt securities, except for specified obligations, including obligations to:

• provide for payment;
• register the transfer or exchange of debt securities of the series;
• replace stolen, lost or mutilated debt securities of the series;
• pay principal of and premium, if any, and interest on any debt securities of the series;
• maintain paying agencies;
• hold monies for payment in trust;
• recover excess money held by the trustee;

12

• compensate and indemnify the trustee; and
• appoint any successor trustee.

In order to exercise our rights to be discharged, we must deposit with the trustee money or government obligations sufficient to pay all the principal of, any premium, if any, and interest on, the debt securities of the series on the dates payments are due.

We will issue the debt securities of each series only in fully registered form without coupons and, unless we provide otherwise in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indenture provides that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company, or DTC, or another depositary named by us and identified in the applicable prospectus supplement with respect to that series. To the extent the debt securities of a series are issued in global form and as book-entry, a description of terms relating to any book-entry securities will be set forth in the applicable prospectus supplement.

At the option of the holder, subject to the terms of the indenture and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

Subject to the terms of the indenture and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will impose no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

• issue, register the transfer of, or exchange any debt securities of that series during a period beginning at the opening of business 15 days before the day of mailing of a notice of redemption of any debt securities that may be selected for redemption and ending at the close of business on the day of the mailing; or
• register the transfer of or exchange any debt securities so selected for redemption, in whole or in part, except the unredeemed portion of any debt securities we are redeeming in part.

The trustee, other than during the occurrence and continuance of an event of default under the indenture, undertakes to perform only those duties as are specifically set forth in the indenture. Upon an event of default under the indenture, the trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs. Subject to this provision, the trustee is under no obligation to exercise any of the powers given it by the indenture at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur.

Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest.

13

We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check or wire transfer to the holders. Unless we otherwise indicate in the applicable prospectus supplement, we will designate the corporate trust office of the trustee as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the trustee for the payment of the principal of or any premium or interest on any debt securities that remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.

The indenture and the debt securities will be governed by and construed in accordance with the internal laws of the State of New York, except to the extent that the Trust Indenture Act is applicable.

We can issue securities in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have securities registered in their own names on the books that we or any applicable trustee, depository or warrant agent maintain for this purpose as the "holders" of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names, as "indirect holders" of those securities. As we describe below, indirect holders are not legal holders, and investors in securities issued in book-entry form or in street name will be indirect holders.

We may issue securities in book-entry form only, as we will specify in the applicable prospectus supplement. This means securities may be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary's book-entry system. These participating institutions, which are referred to as participants, in turn hold beneficial interests in the securities on behalf of themselves or their customers.

Only the person in whose name a security is registered is recognized as the holder of that security. Securities issued in global form will be registered in the name of the depositary or its participants. Consequently, for securities issued in global form, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.

As a result, investors in a book-entry security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary's book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not legal holders, of the securities.

We may terminate a global security or issue securities in non-global form. In these cases, investors may choose to hold their securities in their own names or in "street name." Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account the investor maintains at that institution.

For securities held in street name, we will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be indirect holders, and not legal holders, of those securities.

14

Legal Holders

Our obligations, as well as the obligations of any applicable trustee and of any third parties employed by us or a trustee, run only to the legal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.

For example, once we make a payment or give a notice to the legal holder, we have no further responsibility for the payment or notice even if that holder is required, under agreements with depositary participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the holders to amend an indenture, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of the indenture or for other purposes. In such an event, we would seek approval only from the legal holders, and not the indirect holders, of the securities. Whether and how the legal holders contact the indirect holders is up to the legal holders.

If you hold securities through a bank, broker or other financial institution, either in book-entry form or in street name, you should check with your own institution to find out:

• how it handles securities payments and notices;
• whether it imposes fees or charges;
• how it would handle a request for the holders' consent, if ever required;
• whether and how you can instruct it to send you securities registered in your own name so you can be a holder, if that is permitted in the future;
• how it would exercise rights under the securities if there were a default or other event triggering the need for holders to act to protect their interests; and
• if the securities are in book-entry form, how the depositary's rules and procedures will affect these matters.

A global security is a security that represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.

Each security issued in book-entry form will be represented by a global security that we deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, DTC will be the depositary for all securities issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under "Special Situations When a Global Security Will Be Terminated." As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a legal holder of the security, but only an indirect holder of a beneficial interest in the global security.

If the prospectus supplement for a particular security indicates that the security will be issued in global form only, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.

As an indirect holder, an investor's rights relating to a global security will be governed by the account rules of the investor's financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.

15

If securities are issued only in the form of a global security, an investor should be aware of the following:

• An investor cannot cause the securities to be registered in the investor's name and cannot obtain non-global certificates for the investor's interest in the securities, except in the special situations we describe below.
• An investor will be an indirect holder and must look to the investor's own bank, broker or other financial institution for payments on the securities and protection of the investor's rights relating to the securities, as we describe above.
• An investor may not be able to sell interests in the securities to some insurance companies and to other institutions that are required by law to own their securities in non-book-entry form.
• An investor may not be able to pledge the investor's interest in a global security in circumstances where certificates representing the securities must be delivered to the lender or other beneficiary of the pledge in order for the pledge to be effective.
• The depositary's policies, which may change from time to time, will govern payments, transfers, exchanges and other matters relating to an investor's interest in a global security. We and any applicable trustee have no responsibility for any aspect of the depositary's actions or for its records of ownership interests in a global security. We and the trustee also do not supervise the depositary in any way.
• The depositary may, and we understand that DTC will, require that those who purchase and sell interests in a global security within its book-entry system use immediately available funds, and your broker, bank or other financial institution may require you to do so as well.
• Financial institutions that participate in the depositary's book-entry system, and through which an investor holds its interest in a global security, may also have their own policies affecting payments, notices and other matters relating to the securities. There may be more than one financial intermediary in the chain of ownership for an investor. We do not monitor and are not responsible for the actions of any of those intermediaries.

In a few special situations described below, the global security will terminate, and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own brokers, banks or other financial institutions to find out how to have their interests in securities transferred to their own name, so that they will be direct holders. We have described the rights of holders and street name investors above.

The global security will terminate when the following special situations occur:

• if the depositary notifies us that it is unwilling, unable or no longer qualified to continue as depositary for that global security and we do not appoint another institution to act as depositary within 90 days;
• if we notify any applicable trustee that we wish to terminate that global security; or
• if an event of default has occurred with regard to securities represented by that global security and has not been cured or waived.

The applicable prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the prospectus supplement. When a global security terminates, the depositary, and not we or any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.

We may sell our securities covered by this prospectus in any of three ways (or in any combination):

• to or through underwriters or dealers;
• directly to one or more purchasers; or
• through agents.

We may distribute the securities:

• from time to time in one or more transactions at a fixed price or prices, which may be changed from time to time;
• at market prices prevailing at the time of sale;
• at prices related to the prevailing market prices; or
• at negotiated prices.

16

Each time we offer and sell securities covered by this prospectus, we will provide a prospectus supplement or supplements that will describe the method of distribution and set forth the terms of the offering, including, to the extent applicable:

• the name or names of any underwriters or agents;
• the amounts of securities underwritten or purchased by each of them;
• the purchase price of securities and the proceeds we will receive from the sale;
• any over-allotment options under which underwriters may purchase additional securities from us;
• any underwriting discounts or commissions or agency fees and other items constituting underwriters' or agents' compensation;
• the public offering price of the securities;
• any discounts, commissions or concessions allowed or reallowed or paid to dealers; and
• any securities exchange or market on which the securities may be listed.

Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may be changed from time to time. We may determine the price or other terms of the securities offered under this prospectus by use of an electronic auction. We will describe how any auction will determine the price or any other terms, how potential investors may participate in the auction and the nature of the obligations of the underwriter, dealer or agent in the applicable prospectus supplement.

Underwriters or dealers may offer and sell the offered securities from time to time in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. If underwriters or dealers are used in the sale of any securities, the securities will be acquired by the underwriters or dealers for their own account and may be resold from time to time in one or more transactions described above. The securities may be either offered to the public through underwriting syndicates represented by managing underwriters, or directly by underwriters or dealers. Generally, the underwriters' or dealers' obligations to purchase the securities will be subject to certain conditions precedent. The underwriters or dealers will be obligated to purchase all of the securities if they purchase any of the securities, unless otherwise specified in the prospectus supplement. We may use underwriters with whom we have a material relationship. We will describe the nature of any such relationship in the prospectus supplement, naming the underwriter.

We may sell the securities through agents from time to time. The prospectus supplement will name any agent involved in the offer or sale of the securities and any commissions we pay them. Generally, any agent will be acting on a best efforts basis for the period of its appointment. We may authorize underwriters or agents to solicit offers by certain purchasers to purchase the securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. The contracts will be subject only to those conditions set forth in the prospectus supplement, and the prospectus supplement will set forth any commissions we pay for solicitation of these contracts.

Agents, dealers and underwriters may be entitled to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, or to contribution with respect to payments which the agents, dealers or underwriters may be required to make in respect thereof. Agents, dealers and underwriters may be customers of, engage in transactions with, or perform services for us in the ordinary course of business.

All securities we may offer, other than our common stock, will be new issues of securities with no established trading market. Any underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities.

Any underwriter may engage in overallotment, stabilizing transactions, short covering transactions and penalty bids in accordance with Regulation M under the Exchange Act. Overallotment involves sales in excess of the offering size, which create a short position. This short sales position may involve either "covered" short sales or "naked" short sales. Covered short sales are short sales made in an amount not greater than the underwriters' over-allotment option to purchase additional securities in this offering described above. The underwriters may close out any covered short position either by exercising their over-allotment option or by purchasing securities in the open market. To determine how they will close the covered short position, the underwriters will consider, among other things, the price of securities available for purchase in the open market, as compared to the price at which they may purchase securities through the over-allotment option. Naked short sales are short sales in excess of the over-allotment option. The underwriters must close out any naked short position by purchasing securities in the open market. A naked short position is more likely to be created if the underwriters are concerned that, in the open market after pricing, there may be downward pressure on the price of the securities that could adversely affect investors who purchase securities in this offering. Stabilizing transactions permit bids to purchase the underlying security for the purpose of fixing the

17

price of the security so long as the stabilizing bids do not exceed a specified maximum. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a covering transaction to cover short positions.

Any underwriters who are qualified market makers on The NASDAQ Capital Market may engage in passive market making transactions in our common stock, preferred stock, warrants and debt securities, as applicable, on The NASDAQ Capital Market in accordance with Rule 103 of Regulation M, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the securities. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker's bid, however, the passive market maker's bid must then be lowered when certain purchase limits are exceeded.

Similar to other purchase transactions, an underwriter's purchase to cover the syndicate short sales or to stabilize the market price of our securities may have the effect of raising or maintaining the market price of our securities or preventing or mitigating a decline in the market price of our securities. As a result, the price of our securities may be higher than the price that might otherwise exist in the open market. The imposition of a penalty bid might also have an effect on the price of the securities if it discourages resales of the securities.

Neither we nor the underwriters makes any representation or prediction as to the effect that the transactions described above may have on the price of the securities. If such transactions are commenced, they may be discontinued without notice at any time.

The validity of the securities being offered by this prospectus will be passed upon for us by Jolie Kahn, Esq., Philadelphia, Pennsylvania.

The consolidated financial statements incorporated in this prospectus by reference to the Annual Report on Form 10-K for the fiscal year ended June 30, 2016, have been so incorporated in reliance on the report of Crowe Horwath LLP, independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

This prospectus, which constitutes a part of the registration statement, does not contain all of the information set forth in the registration statement or the exhibits which are part of the registration statement. For further information with respect to us and the securities offered by this prospectus, we refer you to the registration statement and the exhibits filed as part of the registration statement. We file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy any document we file with the SEC at the SEC's public reference room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1.800.SEC.0330 for further information on the operation of the public reference room. Our SEC filings are also available to the public at the SEC's website at www.sec.gov. We also maintain a website at www.swseedco.com. The information contained in, or that can be accessed through, our website is not part of this prospectus.

The SEC allows us to "incorporate by reference" information that we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this prospectus. Information in this prospectus supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus, while information that we file later with the SEC will automatically update and supersede the information in this prospectus. We also incorporate by reference into this prospectus the following documents as well as all documents (other than current reports or portions thereof furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items and other portions of documents that are furnished, but not filed, pursuant to applicable rules promulgated by the SEC) that are filed by us with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (i) after the date of the initial filing of the registration statement of which this prospectus is a part and prior to effectiveness of the registration statement, and (ii) after the effectiveness of the registration statement but prior to the termination of the offering of the securities covered by this prospectus:

18

• our Annual Report on Form 10-K for the fiscal year ended June 30, 2016, filed with the SEC on September 15, 2016;
• the information specifically incorporated by reference into our Annual Report on Form 10-K for the fiscal year ended June 30, 2016, from our Definitive Proxy Statement on Schedule 14A relating to our 2016 Annual Meeting of Stockholders, filed with the SEC on October 28, 2016;
• our Quarterly Report on Form 10-Q for the quarter ended September 30, 2016, filed with the SEC on November 10, 2016;
• our Current Reports on Form 8-K filed with the SEC on October 6, 2016 and December 14, 2016; and
• the description of our common stock contained in our registration statement on Form 8-A, filed with the SEC on April 23, 2010, including any amendments and reports filed for the purpose of updating such description.

You may request a copy of all documents that are incorporated by reference in this prospectus by writing or telephoning us at the following address and number: S&W Seed Company, 7108 North Fresno Street, Suite 380, Fresno, CA 93720; telephone (559) 884-2535. We will provide copies of all documents requested (not including exhibits to those documents, unless the exhibits are specifically incorporated by reference into those documents or this prospectus) without charge.

In accordance with Rule 412 of the Securities Act, any statement contained in a document incorporated by reference herein shall be deemed modified or superseded to the extent that a statement contained herein or in any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement.

19

PART II

The following table sets forth the estimated costs and expenses, other than the underwriting discounts and commissions, payable by S&W Seed Company (the "Registrant") in connection with the offering of the securities being registered. All the amounts shown are estimates, except for the Securities and Exchange Commission ("SEC") registration fee.

* These fees are calculated based on the securities offered and the number of issuances and accordingly cannot be estimated at this time.