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Seed Library at the Milwaukee Area Technical College: Collecting and Donating Seeds

Donating to the Seed Library


  1. Seed Collection and Donation Form - Complete and Submit.
  2. You can "return" or donate sealed, contained seeds to the MATC Seed Library at the MATC Mequon Campus Library, 5555 Highland Rd in Room A282 during our Monday - Friday Open Hours. Visitor parking is available at the north entrance, near the flagpole.

  3. Always save seeds from the healthiest plants. Try to save from as many plants as you can to increase genetic diversity.

  4. Your plants need to bolt/go to seed, in order for you to be able to collect them.

  5. Dry: Make sure seeds are dry and clean. Remove as much of the chaff as possible.

  6. Only return seeds from plants that you know how to save properly. "Super Easy" seeds can be fairly reliably saved without cross-pollination (and unintentional hybridization).  

    • "Super easy" seeds include tomatoes, beans, peas and lettuce.

    • Do not return seeds from the brassica (ex. broccoli, cauliflower, kale, brussel sprouts, cabbage) or cucurbit (ex. cucumbers, squash, melons) families unless you have taken appropriate steps to prevent cross-pollination, such as hand-pollinating.


Specific seed collecting tips follow on this page.

Cole Crops


Biennial seed saving. Isolate broccoli by 1 mile (5,200 feet) from all other Brassica oleracea. In fall remove plants from soil and pot them in sand. Store plants between 32-40° F. Transplant back outdoors in early spring and allow to bolt. Harvest seed pods when dry and clean by hand. - from Urban Farmer



Leave your seed corn in place when you harvest your eating corn. Seed corn needs at least one to two more months in the field before it is harvested.

Watch for the seed corn's ear husks to begin to dry and turn brown. Harvest the ears on the next dry day and before the first frost. Pull each ear from the plants, pile the ears in a large basket and carry the basket into your garage or other sheltered area.

Pull back the husks of each ear to expose the kernels. Use the husks to braid three or four ears together in a bunch. Repeat the procedure until all the seed corn is bunched. Hang the bunches in a room where the air is dry and warm but not too hot. Air-drying the corn kernels helps to prevent mold.

Check the dried ears three months later for off-color kernels that could indicate bad or cross-pollinated corn. Remove these kernels and throw them away; if one ear has many off-color kernels, remove and dispose of the entire ear.

Shell the kernels from the remaining ears. Use one hand to hold an ear over a large bowl and twist off the kernels with your other hand. Continue twisting until all the kernels have fallen into the bowl. The kernels will be very wrinkled.

Transfer the kernels into a rodent-proof container. A large glass jar or metal canister works well. Store the container in a dry, cool area until planting time, after the ground warms.

Things You Will Need

  • Large basket

  • Large bowl

  • Rodent-proof container


It is critical to save seeds from many corn plants to maintain genetic diversity in your seed corn and to prevent inbreeding depression, a condition that causes new corn to be short and produce few ears. Plant at least 100 corn stalks in a block formation to obtain good pollination among them. Keep one out of every two ears for seed corn; harvest the rest for eating.


Although diversity within a corn variety is essential, it is also important to isolate your corn variety from cross-breeding with other varieties. If neighbors also grow corn, plant your crop as far away as possible from their gardens to prevent pollination by wind. Alternatively, select corn that pollinates at different times than your neighbors' corn.


Spengler, Teo. "How to Save Sweet Corn to Plant Next Year." Home Guides | SF Gate, 26 January 2018.

Cucumbers & Squash


HARVEST: Squash must be fully mature before harvested for seed production. This means that summer squashes must be left on the vine until outer shell hardens. Allow to cure 3-4 additional weeks after harvest to encourage further seed ripening.

PROCESS: Chop open hard-shelled fruits and scoop out seeds. Rinse clean in wire strainer with warm, running water. Dry with towel and spread on board or cookie sheet to complete drying.

-from International Seed Saving Institute


For the most optimal cucumber seed collection, select from only disease free plants which have the most flavorful fruit. Seed must be harvested when the fruit is mature, so allow the cucumber to languish on the vine past its eating stage – near the end of the growing season. Fruit will be orange or yellow when fully ripe and ready to pluck mature seeds from. In order to harvest seeds from fleshy fruits such as cukes or tomatoes, the wet method of removal should be applied. Remove the seeds and allow them to ferment in a bucket for three days with a small amount of warm water in order to remove the gel coating surrounding the seeds. Stir this concoction daily. This fermentation process kills viruses and separates the good seeds from the pulp and the bad seeds. The good seeds will sink to the bottom while the bad seeds and pulp float at the surface. Pour off the pulp, water, mold and bad seeds carefully after your three days have passed. Remove the good seed and spread them on a screen or on paper towels to dry thoroughly. Once completely dry, your seeds can be stored in envelopes or a glass jar with a clear label specifying the date and variety. Place the container in the freezer for two days to kill any residual pests and then store in a cool, dry place such as the refrigerator. Seed viability decreases over time, so be sure to use the seed within the next three years. - from Gardening Know How

Read more at Gardening Know How: Cucumber Seed Collection: Tips For Harvesting & Saving Seeds From Cucumber





Cut seed heads when they are becoming dry and hang them upside-down in large paper bags or over tarps to collect the tiny seeds. The dried heads can easily be crumbled in the hands and the chaff gently blown away if you're in a hurry.

Amaranth seeds can last for many years if properly stored, and can sprout in the garden even after several years in the soil.



For okra seed harvesting, the seed pods must dry on the vine and beginning to crack or split. At that point, you can remove the pods and split or twist them. The seeds will come out easily, so keep a bowl nearby. Since no fleshy vegetable matter clings to the seeds, you don’t need to wash them. Instead, dry the seeds in the open air for a few days, then store them in an airtight jar in the refrigerator. Although some okra seeds can remain viable for up to four years, many do not. It’s best to use collected okra seeds the next growing season. For best results, soak the seeds in water for a day or two before planting.

Read more at Gardening Know How: Collecting Okra Seeds – How To Save Okra Seeds For Planting Later



Onions & Leeks


Onion seeds are not typically difficult to grow or to collect, but keep in mind that they are a biennial crop, meaning that they seed once every two years.

Life Cycle: Biennial

Recommended Isolation Distance: When saving seeds from onion, separate varieties by at least 800 feet up to ½ mile. To produce seed from onion, select as many perfect onions as you can spare for seed production and store them through winter in a cool, dry, dark place. Replant them in early spring at the same bulb depth and spacing as when they were harvested.

Recommended Population Sizes: To ensure viable seeds, save seeds from at least 5 plants. To maintain a variety over time, save seeds from between 20-50 plants.

Assessing Seed Maturity: Watch first for flowers and then for seed heads to form during the late summer of the second season. Wait for the seed heads to dry. Most of the flowers will be dry, and the seeds will begin to fall out on their own.

Harvesting: After the plants bloom and seed heads begin to dry, gather the heads in a paper bag. Most of the seeds will fall out on their own; shake the bag to free the remainder of the seeds.

Cleaning and Processing: Separate the seeds from the stems and other matter that makes up the seed head. Allow the seeds to air-dry for a few days before storing the seeds in a cool, dry place.

Storage and Viability: When stored in a cool, dark, dry place, onion seeds will remain viable for 2 years.

-from Seed Savers Exchange

Peas & Beans


Save pea and bean seeds by allowing the pods to ripen on the plants until they're dry and starting to turn brown, with the seeds rattling inside. This may be as long as a month after you would normally harvest the peas or beans to eat. Strip the pods from the plants and spread them out to dry indoors. They should dry at least two weeks before shelling, or you can leave the seeds in the pods until planting time.