This prospectus relates to the offer and resale from time to time by the selling stockholder named in this prospectus of up to 8,842,717 shares of our common stock.

The selling stockholder may sell the shares of common stock described in this prospectus in a number of different ways and at varying prices. We provide more information about how the selling stockholder may sell its shares of common stock in the section entitled "Plan of Distribution" on page 5. The selling stockholder will bear all commissions and discounts, if any, attributable to the sale or disposition of the shares, or interests therein. We will bear all costs, expenses and fees in connection with the registration of the shares. We will not be paying any underwriting discounts or commissions in this offering.

We are not selling any shares of common stock under this prospectus and will not receive any proceeds from the sale of the shares by the selling stockholder.

Our common stock is listed on The Nasdaq Capital Market under the symbol "SANW." On February 27, 2019, the last reported sale price of our common stock on The Nasdaq Capital Market was $3.00 per share.

A prospectus supplement may add, update, or change information contained in this prospectus. You should carefully read this prospectus, any applicable prospectus supplement, and the information incorporated by reference in this prospectus and any applicable prospectus supplement before you make your investment decision.

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ABOUT THIS PROSPECTUS

We urge you to read carefully this prospectus, together with the information incorporated herein by reference as described under the heading "Where You Can Find More Information," before buying any of the securities being offered.

Neither we nor the selling stockholder has authorized anyone to provide you with different information, and if anyone provides, or has provided you, with inconsistent information, you should not rely on it. The selling stockholder is offering to sell, and seeking offers to buy, shares of our common stock, only in jurisdictions where offers and sales are permitted. The information contained in this prospectus, as well as the information filed previously with the Securities and Exchange Commission (the "SEC"), and incorporated herein by reference, is accurate only as of the date of the document containing the information, regardless of the time of delivery of this prospectus or any applicable prospectus supplement or any sale of our common stock.

A prospectus supplement may add to, update or change the information contained in this prospectus. You should read both this prospectus and any applicable prospectus supplement together with additional information described below under the heading "Where You Can Find More Information." In this prospectus, references to the "Company," "S&W Seed," "registrant," "we," "us," and "our" refer to S&W Seed Company. The phrase "this prospectus" refers to this prospectus and any applicable prospectus supplement, unless the context requires otherwise.

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CAUTIONARY NOTE REGARDING FORWARD LOOKING STATEMENTS

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 (the "Securities Act"), and Section 21E of the Securities Exchange Act of 1934, as amended (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 "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" below 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.

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PROSPECTUS SUMMARY

Founded in 1980 and headquartered in Sacramento, 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 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 been granted four patents by the U.S. Patent and Trademark Office.

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, 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;
• 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 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 and through an expansion of our sales and marketing efforts generally; and
• implementing a stevia breeding program focused on the potential development of 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 ("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, S&W Seed Company Australia Pty Ltd (f/k/a Seed Genetics International Pty Ltd, "S&W Australia") in April 2013, which greatly expanded our production capabilities and geographic diversity;
• the acquisition of the alfalfa production and research facility assets and conventional (non-GMO) alfalfa germplasm from 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;

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• the acquisition, in May 2016, of the assets and business of SV Genetics Pty Ltd ("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;
• the acquisition of a portfolio of sorghum germplasm in April 2018 to expand our portfolio of sorghum products to include biofuel types; and
• the acquisition of substantially all of the assets of Chromatin in October 2018, to accelerate and substantially expand our penetration into the hybrid sorghum market, and enable us to expand our production and research and our product development capabilities.

We believe our 2013 combination with S&W Australia 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, our April 2018 acquisition of a portfolio of sorghum germplasm, and our October 2018 acquisition of the assets and business of Chromatin signal management's commitment to our strategy of identifying opportunities to diversify our product lines and improve our gross margins.

We continue to have a long-term distribution agreement with DuPont Pioneer regarding conventional (non GMO) varieties, the term of which extends into 2024. Our production agreement with DuPont Pioneer (relating to GMO-traited varieties) terminates on May 31, 2019. As a result, DuPont Pioneer's minimum purchase commitments from us will be reduced by approximately $6 million annually, commencing with our Fiscal Year 2020. Although the production agreement will terminate on May 31, 2019, we expect that the DuPont Pioneer distribution agreement will continue to be a significant source of the Company's annual revenue through December 2024.

We are in discussions with DuPont Pioneer regarding the orderly transition of activities previously conducted by us under the production and research agreements (relating to GMO-traited varieties), as well as the possibility of certain ongoing commercial relationships between us relating to GMO-traited varieties, among other things.

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.

In April 2013, we, together with our wholly-owned subsidiary, S&W Holdings Australia Pty Ltd, an Australia corporation (f/k/a S&W Seed Australia Pty Ltd), consummated an acquisition of all of the issued and outstanding shares of Seed Genetics International Pty Ltd, an Australia corporation ("SGI"), from SGI's shareholders. In April 2018, SGI changed its name to S&W Seed Company Australia Pty Ltd.

Our principal business office is located at 106 K Street, Suite 300, Sacramento, California 95814, and our telephone is number (559) 884-2535. S&W Australia'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.

On September 5, 2018, we entered into a Securities Purchase Agreement (the "Purchase Agreement") with MFP Partners, L.P. ("MFP"), pursuant to which we sold to MFP (i) 1,607,717 shares of our common stock (the "Initial Closing Shares") to MFP at a purchase price of $3.11 per share at an initial closing held on September 5, 2018, for aggregate gross proceeds of approximately $5.0 million, and (ii) 7,235 shares of our newly designated Series A Convertible Preferred Stock at a purchase price of $3,110 per share (the "Preferred Shares") at a second closing completed on October 23, 2018 (the "Second Closing Date"), for aggregate gross proceeds of approximately $22.5 million. At our November 20, 2018 special meeting of stockholders, our stockholders approved the issuance of 7,235,000 shares of our common stock (together with the Initial Closing Shares, the "Shares") to MFP upon conversion of the Preferred Shares, which was effective as of November 20, 2018.

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Concurrently with the execution and delivery of the Purchase Agreement, we entered into a Registration Rights Agreement (the "Registration Rights Agreement") with MFP. Pursuant to the Registration Rights Agreement, we agreed to, among other things, (i) file a registration statement with the SEC within 75 business days of the Second Closing Date to cover the resale by MFP of the Shares, (ii) cause such registration statement to become effective as soon as practicable following the filing thereof and (iii) take all other actions as may be necessary to keep such registration statement continuously effective during the timeframes set forth in the Registration Rights Agreement. If we fail to comply with certain obligations with respect to filing and securing effectiveness of such registration statement, we would be obligated to pay liquidated damages to MFP in the amount of 1% of MFP's aggregate purchase price of the Shares for each applicable 30 day period, up to an aggregate maximum of 4%, so long as the event giving rise to the damages remains uncured, all as set forth in the Registration Rights Agreement.

The Registration Statement of which this prospectus is a part relates to the resales of the Shares in connection with the transactions described above, with MFP being the selling stockholder.

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RISK FACTORS

An investment in our common stock involves a high degree of risk. Prior to making a decision about investing in our common stock, you should consider carefully the specific risk factors discussed in the sections entitled "Risk Factors" contained in our most recent Annual Report on Form 10-K or Quarterly Report on Form 10-Q, as filed with the SEC, which are incorporated in this prospectus by reference in their entirety, as well as any amendment or updates to our risk factors reflected in subsequent filings with the SEC, including any prospectus supplement hereto. These risks and uncertainties are not the only risks and uncertainties we face. Additional risks and uncertainties not presently known to us, or that we currently view as immaterial, may also impair our business. If any of the risks or uncertainties described in our SEC filings or any additional risks and uncertainties actually occur, our business, financial condition, results of operations and cash flow could be materially and adversely affected. In that case, the trading price of our common stock could decline and you might lose all or part of your investment.

The proceeds from the sale of shares of common stock offered pursuant to this prospectus are solely for the account of the selling stockholder. We will not receive any proceeds from the sale of shares by the selling stockholder.

The selling stockholder, or its pledgees, assignees, or successors-in-interest, is offering for resale, from time to time, up to an aggregate of 8,842,717 shares of our common stock. The following table sets forth certain information with respect to beneficial ownership of our common stock as of February 8, 2019 by the selling stockholder, as determined in accordance with Rule 13d-3 of the Exchange Act. This information has been obtained from the selling stockholder or in Schedules 13G or 13D and other public documents filed with the SEC.