Spring 2010
2009 Farmer-to-Farmer Conference Presentation by Jodi Lew-Smith and Jim Gerritsen

Chives grown for seed at High Mowing Organic Seeds
A crop of chives grown for seed at High Mowing Organic Seeds in Vermont. Photo by Heather Jerrett.

By Jean English

Finding reliable sources of quality organic seed continues to challenge farmers, and market development for organic seed has been slower than anticipated. At the 2009 Farmer-to-Farmer Conference, cosponsored by MOFGA and the University of Maine Cooperative Extension, seed producers and consumers discussed issues of organic seed quality and availability with Jodi Lew-Smith, Director of Research and Production for Vermont-based High Mowing Organic Seeds, and Jim Gerritsen, whose family’s Wood Prairie Farm produces organic seed potatoes and seed of other vegetable crops, and who is president of the Organic Seed Alliance.

Dry-seeded crops, said Lew-Smith, need dry weather at harvest to avoid fungal diseases, so they are generally grown in California, Oregon, Washington and Idaho. Idaho is particularly suited to crops such as beans, peas and onions that need more heat for the seed to “finish.” Finishing means ensuring that quality by maturing the seed, usually in the field.

Certain dry-seeded crops (e.g., spinach, beets, chard and cole crops) need cool temperates when they’re setting seeds, because their anthers and stamens are sensitive to heat. They do well in the consistently cool Pacific Northwest. Cauliflower, Lew-Smith added, is the most finicky seed crop to grow and does best on one strip on the coast of the Olympic Peninsula in Washington.

Wet-seeded crops need moisture during seed production. Some yield better with more heat than we normally have in New England. So, for example, you can grow tomatoes for seed in New England, but the same size crop will yield far more seed in California. Most tomato and pepper seed crops are grown in California, Israel and Chile.

Defining and Ensuring Quality

Seed quality is measured by its germination rate – usually 80 percent for most vegetable seeds and 70 for flowers and herbs. Federal standards (below which you cannot sell seed) are lower than this; High Mowing’s standards are higher – ideally above 90 percent. This ensures that most seed will live longer than one year, will have greater vigor, and will germinate quickly, uniformly, vigorously and with a full set of seedling parts (cotyledons, primary roots, secondary roots, etc.).

“Seed is metabolizing at a very slow rate all the time,” said Lew-Smith. “Our goal is to keep that rate as low as possible by dry, cool conditions.”

 Without conditions that enable seed maturation, resultant seed typically germinates at around 50 percent, lacks vigor and often molds as the seed leaks metabolites because its food stores weren’t metabolized into compounds that store well.

Once seed is finished in the field, it must be moved quickly from wet to dry conditions during harvest and processing. Even dry seed is too moist right from the field and must be dried quickly to about 10 percent moisture or less. Heat can help, but seed must not get so hot during drying that it bakes or enters extended dormancy. About 90 F is the cutoff at High Mowing; 80 F is perfect.

Once dry, seed should be stored in cool, dry conditions: temperatures in the 40s or 50s and a relative humidity around 20 percent – in a cool basement in a sealed container, for example. Lew-Smith said that seedsman Frank Morton gauges seed moisture by putting a piece of a brown paper bag in with the seed. If it comes out somewhat mushy, the seed is too wet; if it comes out crinkly, the seed is dry.

When seed is stored in a freezer, Lew-Smith said that condensation upon removal from the freezer can be a problem.

Seed Production in New England

Wet-Seeded Crops

Among wet-seeded crops, squashes are easy to grow and can produce reliable seed quality and quantity here – depending on the variety. ‘Long Island Cheese,’ a butternut category of Cucurbita moschata squash, comes from a tropical climate and needs a little more heat and a longer season to finish than some other squashes.

“When we grow those types, we tend to start them early under cover,” said Lew-Smith, “and cover them at the end of the season. Even then, we rarely see germination over 90 percent; typically we get the 80s. But something like a ‘Red Kuri,’ zucchinis, acorns are relatively short-season, they’ll finish here and seed quality is good.”

To avoid cross-pollination, Lew-Smith said that the textbook recommendation is 2 miles between varieties within a squash group, but 1 mile is probably fine, especially if you have tree breaks.

All cucurbits – squashes, melons, cucumbers – cross within their group, but groups don’t cross with one another. All C. pepo (pumpkins, zucchinis, acorns and some other winter squashes) cross with each other, and pepos are the hardest ones to isolate. C. maxima (buttercups, kabochas, some specialty pumpkins) can cross with each other; and C. moschata (butternuts and some specialty pumpkins, such as ‘Long Island Cheese’) can cross and need to be isolated from one another, but they can be grown in the same field as melons or cucumbers; and a moschata, maxima and pepo grown in the same field won’t cross.

Plants can also be caged or hand-pollinated to avoid unwanted cross-pollination. Gerritsen added that squashes can be isolated in time by growing a three-year supply of one variety one year, of another the next year, etc.

Melons (including watermelons) need plastic and row cover until they flower to get enough heat, Lew-Smith continued. Seed quality is reliable but yields are highly variable. Lew-Smith was surprised that High Mowing’s watermelons did so well in 2009. “It made me think that they need more water than we give them” rather than more heat.

Cucumbers grow well, their seed quality is reliable, and yields are usually very good, so this is the best and easiest seed crop to grow here – but varieties must be separated. A yellow, overgrown cucumber is ready to harvest for seed.

Tomatoes intercross at a small rate – 1 to 3 percent – and peppers, 5 to 6 percent, so High Mowing gives tomatoes 50 to 100 feet of isolation, and peppers, 500 to 600 feet. To grow these for quality seed, High Mowing plants them on plastic and sprays with sulfur to control early blight, then with copper if late blight arrives. Still, seed yields are low in New England, except for cherry types, but seed quality is usually good. High Mowing ferments the seeds to remove the gel around them, and defuzzes them. Home gardeners can just put the seed in a bowl and wash the gel off with water. The gel doesn’t prevent germination, but it can get mildewy and it makes the seeds sticky and a little difficult to manage.

Peppers need plastic and row covers (partly to keep tarnished plant bugs from damaging flowers). They get fewer diseases than tomatoes. Bell peppers must be red to produce a good seed crop; you can pick them green and let them turn red in a greenhouse. Seed yields are best for hot types, and the quality is usually good. The seeds are easy to harvest and dry, and they don’t need to be cleaned, unless you crush the fruit to harvest the seed. One grower said he sells the cut pepper flesh to a deli and keeps the seeds.

Dry-Seeded Crops

Dry-seeded crops with pods, such as annual brassicas, arugula, Asian greens and many flowers, do well and yield well in New England. Their pods help protect them from fungi. Broccoli is marginal because it requires a longer season to mature. Most annual greens need some cold, so they must be in the ground early. High Mowing seeds them in March and tries to get them out of the greenhouse by the end of April so that they get frosted, tricking them into “thinking” they’ve gone through a winter.

“Some need more tricking than others,” said Lew-Smith. The seed is done in August. Broccoli is treated the same way but doesn’t finish until late September.

Seeds of dry-seeded crops without pods, such as lettuce, spinach and calendula, are difficult to get to a high enough germination rate to sell. When High Mowing grows them, they’re in a hoophouse, which is not economical on a large scale.

Specialty greens in unusual families, such as chrysanthemums, can be grown experimentally. Nobody is growing them organically, so High Mowing produces a lot of its own seed for these crops. “If somebody else wanted to figure out how to do organic production of corn salad, great!” said Lew-Smith.

Flowers with pods, such as nigella, nicotiana and biennial sweet William (dianthus), are reliable but their seed quality is not always good.

Sunflowers can be grown well but must be sprayed for weevils in August. High Mowing combines Naturalis, neem and PyGanic.

Perennial bunching onions and chives do well; they stay in the ground over winter, come up quickly in spring, and their seed is ready in August. The plants just require heavy cultivation. Biennial onions can do well but need to be grown one summer, harvested and stored over winter and replanted the next spring; or they can be grown in a hoop house, which High Mowing does with some varieties. Seed isn’t done until fall – which can be wet.

Other herbs can be grown here but High Mowing rarely experiments with them because they’re grown so well (and organically) on the West Coast.

Beans are feasible but the sugar in their pods makes them susceptible to white mold, and yields are highly variable. You may get a good crop one out of four years. They need heat to finish.

Peas are not economical to grow for seed in New England. They’re prone to fungal diseases and need to be staked to get them off the ground.

Edible soybeans (edamame) are difficult here because they require a long season and heat; and deer love them.

Flint corn is easy and can yield well. High Mowing does only open-pollinated varieties.

Early maturing sweet corn can also do well but is more prone to mold, so has to be harvested early and dried fast.

Seed Production at High Mowing

High Mowing uses its isolated fields to clean up genetics of newly added varieties, to manage stock seed for larger production, and to produce some seed, including cucumber.

Most of its squashes are grown on plastic to help ensure that seeds finish during cold, wet years and to help minimize erosion. Cover crops are grown between the rows of plastic. At the end of the season, everything is windrowed and a wet seed extractor is driven alongside the windrow. Squash goes into a hopper and then to a crusher. Seed comes through holes, and the pulp goes back on the fields. The squash seed goes into big drums, then is washed on screens and dried in a greenhouse heated to the 80s, with a lot of fans running.

Brassicas, with their dry seedpods, are harvested by hand onto tarps and are dried in a greenhouse, yielding up to 500 pounds of seed per acre. “If we don’t think broccoli seed is finished,” said Lew-Smith, “we harvest plants with roots on them and bring them into the greenhouse.” Squash seeds, on the other hand, can finish in harvested fruits. A stationary thresher cleans dry seeds from chaff.

Seed Cleaning

Seed is quickly tested as “dirty seed” to make sure it’s worth cleaning and then is cleaned “to purity” (99.5 percent pure) as a minimum. If cleaned seed doesn’t meet germination standards, it is cleaned further, usually on a gravity table that shakes the seed in two directions to separate it by density. By keeping the heavier seed, the germination percentage should increase.

Then, every seed lot is tested for germination at least twice a year. Onions, which don’t have a very long life, and pelleted lettuce get tested three times a year. Seed that doesn’t germinate is composted; seed that is not up to High Mowing’s standards is sold at a discount. Germination is tested in moist towels or, for seeds such as lettuce that need light, in a clear plastic box.

Jim Gerritsen on Wood Prairie Farm’s Seed Production

Jim Gerritsen of Wood Prairie Farm in Bridgewater, Maine, talked about his farm’s seed potato production. (See “On-Farm Seed Production” in the March-May 2009 issue of The MOF&G, at

Wood Prairie’s well-drained sandy loam is ideal for its 12 acres of potatoes grown in a four-year rotation with other crops. When Gerritsen receives calls from seed potato customers who have clay soils, he advises them to add composted leaves or other organic matter to lighten their soil.

Gerritsen is also president of the Organic Seed Alliance, which aims to increase the quality of organic seed available, including addressing the issue of contamination by genetically engineered crops. (See “Organic Seed Alliance May Save Us from Ourselves,” in the Dec. 2008-Feb. 2009 issue of The MOF&G, at

Wood Prairie also grows bread wheat and is an advisor on a $1.3 million, four-year USDA program to identify varieties for growing bread wheat in New England, especially for minimizing disease pressure. “There is a reason why wheat production moved west,” said Gerritsen, citing diseases in Northeast.

In addition to fish fertilizer, the Gerritsens apply a mix of mycorrhizal fungi, T22 Trichoderma, Carouse from International Ag Labs (, which has 50 or more bacteria in it, and a seaweed-based powder. The mixture goes into Gandy boxes (, originally used by other farmers to meter out systemic insecticides down to 3 or 4 pounds per acre of material. The Gerritsens’ mix costs $200 to $300 per acre.

First a fertilizer opener lays down fertilizer, then a seed opener covers the fertilizer and allows the seed to be laid about an inch above that. “That’s where we’re trickling in the Gandy Box mix,” said Gerritsen. “We’re trying to create an environment around the seed piece that is populated with beneficial fungi that will colonize and create this beautiful world of peace and love around the potatoes.”

Their customers say that potatoes grown from Gerritsens’ seed potatoes are yielding better. Gerritsen says that a practitioner keeping careful notes should see a significant difference in seed quality, “largely invisible to the human eye.

“To me, crop agriculture starts with the seed, and quality is absolutely essential.”

Gerritsen said that the size of the seed potato doesn’t affect production until it’s over 3 ounces, so planting one field with 1-1/2-ounce seed and another with 2-3/4-ounce seed means spending twice as much on the larger seed without getting a yield increase.

“Go to Rite Aid and buy one of these $5 diet scales,” said Gerritsen. “We keep one right in the toolbox on the tractor.” They weigh every new variety to see what a 3-ounce piece looks like so that they know to cut big ones in half.

Greensprouting ensures that sprouts will emerge from each piece. “Everybody ought to be greensprouting,” said Gerritsen. Harvesting potatoes 10 days earlier in August after greensprouting them in April is tremendously valuable, he noted. (Greensprouting is described in “On-Farm Seed Production,” cited above.)

The Gerritsens’ potatoes did not get the “big-box blight” that ruined so many potato and tomato crops in 2009, but instead got a strain that came from Canada. Wood Prairie never got summer winds from the east until a few years ago; blight spores now blow in from that direction. Wood Prairie’s potatoes suffered premature defoliation and some yield reduction but did not have blight in the tubers. They used copper to protect the plants.

For those who want to grow a small seed crop, Gerritsen mentioned the Home Garden Seed Association (, which tends to include the smaller seed companies. “A pound of tomato seeds will fill 400, 500 seed packets,” said Gerritsen. “A lot of these seed companies, if they sell 1,000 packets of one variety, that’s a great variety. So if you can grow a couple of pounds of an unusual variety… There are niches out there. The seed industry is in a boom right now.”

Lew-Smith suggested calling a seed company to see what varieties it needs, then working out how to grow the crops. “Then keep growing it. That’s really key.”


Regarding controlling seed-borne bacterial diseases, Lew-Smith recommended producing seed where the disease isn’t a problem; scouting the seed crop for disease symptoms; and treating seed with hot water. When she experimented with other treatments – bleach, Mycoprop, Serenade – none worked as well as hot water. Cooperative Extension recommends a water temperature of 50 C for 25 minutes, but Lew-Smith found that 47 to 48 C for about 20 minutes worked just as well, with time depending on seed type. “It doesn’t work on big seeds, such as melons and squash, but does on smaller seeds, such as tomatoes and brassicas.” Hot water also controlled rhizoctonia on lettuce seeds. A deep fryer, said Lew-Smith, is useful because it maintains a steady temperature; while doing that with a pot of water and a thermometer is difficult.

To harvest beans for seed, Gerritsen related an old neighbor’s method: Rather than planting beans every 2 inches in the row, he planted clumps of 5 or 6 seeds every foot. In the fall when the seed pods dried down 90 percent, he’d cut lengths of sisal baling twine, knot it, and put it through his belt loop with all knots at the top. He’d pull a length off, tie it around the clump of bean plants, leaving a tail 6 to 8 inches long, and then tie an overhand knot on the tail. Then he’d throw the bundle onto the pickup truck. Back at the shed, he’d back up to the door, then delaminate that tail of twine and snag it on 8-penny nails hanging about a foot apart on the rafters where the beans would dry, out of the sun, with good air flow, and where mice couldn’t get at them. Once the beans dried, he’d whack the bundles on the inside of a potato barrel, where 99 percent of them would shatter. “Then you’d have a barrel full of mainly beans, some broken pods, a little bit of dirt and rocks,” said Gerritsen. This material can be winnowed on a windy day or, using Tom Stearns’ method, with a gang of three fans, each with three settings, giving 9 possible settings for fine tuning the breeze. Pour a stream of seeds through the breeze from square boxes or totes. To get the rocks out of his bean seeds, Gerritsen uses a seed cleaner with a hopper and a 6-inch conveyor belt. You can also use screens, said Lew-Smith.

Moderator Becky Sideman said that for home scale, she puts bean plants in grain bags. When they’re dry, she beats the bag, then cuts a hole in the bottom so that the beans come out. Another Farmer-to-Farmer participant suggested driving a truck over the bag.

Grower Kate Newkirk mentioned “The Little Sheller” cleaning and threshing machine from Taylor Manufacturing Co., Inc., in Moultrie, Georgia (, which she has used on beans and wheat. The machine now sells for $399 plus shipping.

Nancy Chandler added that Highmoor Farm has a thresher and other seed cleaning machinery for public use, thanks to the Public Seed Initiative.

The Organic Seed Alliance, said Gerritsen, has created another entity called the Family Farmer Seed Cooperative to support regional cooperation among organic seed growers for growing, marketing and sharing equipment. The cooperative has a couple of seed incubator projects in the West and Northwest that are getting matching grants to buy equipment, and Gerritsen is pushing for one in the East that could buy basic seed equipment, such as a wet seed thresher, that can be shared.

Lew-Smith suggested a wet seed thresher that is not for the home gardener but is great for growers. John Wallace Fabrication of Colusa, California (530-755-8172 cell, 530-458-7360), builds it for about $19,000. He also makes dryers and “can basically make anything.” The thresher has a coner like the big harvesters, said Lew-Smith, and the crusher side can swing away so that hydraulics can tip up the drum side which can then be hosed down quickly. An auger brings seed up from the drum to any bin you want to put there, and the auger cover has a door that easily swings open for cleaning. The whole thing takes 15 minutes to clean, and comes with different size crushers.

Asked about producing oats, Gerritsen advised, “Be sure to plant hulless oats. They don’t yield as high, but then you’re not getting a bunch of hulls either. Ninety-eight percent will be hulless; then you just get rid of that 2 percent that’s a pain – blow it off with fans or screen them out, or, in our case, we’ve got a small-scale hulling machine. These are $1,500-1,800 machines. The next jump is $25,000 to $35,000. Then simply roll them through a roller. Hulled oats require an expensive scalper.”

To remove oats from plant stalks, one grower puts them through a small chipper that empties into a bag, then separates the oats from the chipped stalks by screening or blowing the material.

Gerritsen said the historical (even Biblical) way is to make a flail: Drill a quarter-inch hole in a shovel handle; drill a quarter-inch hole in a piece of hardwood 2 x 2 about 12 inches long; and tie the two together with a piece of quarter-inch nylon rope about 16 to 18 inches long. “ Lay out your wheat or beans or whatever and beat them. Be careful that you don’t hit yourself in the head. You develop a technique where your wood piece comes down and hits [the crop] flat. You want a hard surface, like a concrete pad or a wood floor.”

Regarding the transition from organic vegetable growing to organic seed growing, Lew-Smith said this is generally a lot more challenging than going from being a conventional seed grower to an organic seed grower, “because seed is so challenging, and it’s such a different thing to grow. It’s a whole different mindset. The prospect of growing seed on the side works occasionally for a few people, but as a rule it doesn’t work well.” She suggested that vegetable growers try growing seed on their own for a few years to see if they like the process and if they can produce quality seed.

“Seed requires your attention all season long. You have to get your timing right. You can’t miss your windows. It works easier for wet-seeded vegetables, such as tomatoes; but the problem is, you’ve got to set your best fruit aside for seeds. If you want to sell your best fruit at market and set aside the crummier stuff for seed, it really doesn’t work.”

One grower said he gets seeds out of tomatoes and then processes the fruit into sauce.

Regarding storage, one participant said that he stores seeds in an old refrigerator in an unheated barn to keep rats out and to keep them dry.

Gerritsen noted the rule of thumb for seed storage: The temperature plus the relative humidity should add to less than 100 – so at 40 F, you should have less than 60 percent humidity.

Annual mustard (grown in rotation with potatoes to kill soil-borne pathogens), said one grower, is not just a potential weed problem if it goes to seed, but if it flowers it attracts click beetles, which then lay eggs which become wireworms – a pest of potatoes and other crops. Gerritsen grows biennial rapeseed to avoid any potential weed problem.


Ashworth, Suzanne, Seed to Seed: Seed Saving and Growing Techniques for Vegetable Gardeners, Seed Savers Exchange, 2002

eOrganic, – Web community for organic growers, researchers, etc.

Gerritsen, Jim and Megan and family, Wood Prairie Farm, 49 Kinney Rd., Bridgewater, ME 04735; 207-425-7741; [email protected];

Lew-Smith, Jodi, Ph.D., Director of Research and Production, High Mowing Organic Seeds, Inc., 76 Quarry Rd., Wolcott, VT 05680; 802-472-6174 Ext. 116; 802-472-3201 Fax;

Maynard, Donald and George Hockmuth, Knott’s Handbook for Vegetable Growers, Wiley, 2006

Organic Seed Alliance,; and “Seed Companies Selling Organic Seed” at

Organic Seed and Seed Production articles,

Organic Seed Growers and Trade Association,

Stone, Alex, “Organic Management of Late Blight of Potato and Tomato (Phytophthora infestans),

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