University of Illinois Extension

Seed Collecting and Storing

Collecting and sowing his or her own seeds can be a fun and gratifying experience for the home gardener, says Nancy Pollard, a University of Illinois Extension horticulture educator.

“At first, the details may seem overwhelming,” said Pollard. “Yet, as you gain experience, and are rewarded with new seedlings, you may find yourself inspecting your flowers closely in anticipation, and seed saving could become second nature to you.”

Home gardeners can collect their own seeds from their own plants. Information that is normally found on commercial seed packets can be located in books or websites, she noted.

“While your choices are limited by how many plants grow in a particular garden area, joining a seed exchange group increases the availability of saved seed for your future planting,” she said. “The joyful thought of watching seeds magically sprout next year, or the great disappointment if they fail, encourages us to look into best practices for collecting and storing plant seeds.”

The first step is to choose healthy seedpods and fruits for seed collection. Healthy plants show vigorous growth, exhibit resistance to pests and diseases, produce good quality fruit, and produce high yields.

“As the chosen plants finish flowering, look for swelling seedpods or ripening fruit,” she said. “Wait until it is fully mature. It is important to collect only fully mature or ripened seed. Sometimes, nearly mature seeds may ripen off the plant, if they remain in their seedpods. If picked too early, the embryo will not survive the drying out process, or if picked too late, the wind may blow away the seed.

“Fine, nylon-mesh bags work universally well for collecting seeds and seed structures. Paper bags work well for seeds, cloth bags for panicles or dry fruit, and open baskets for fleshy fruit but be sure not to squash the fruit. Do not let seeds become hot or moldy.”

With dry seed pods, extract the ripe seeds by hanging them upside down over a paper bag in a shaded, dry, airy place and wait for the seeds to fall. An occasional gentle tap will help.

“Cut clustered seed heads such as those of marigolds whole and lay on a newspaper to dry,” Pollard said. “Whenever you harvest your own seed, remove as much of the chaff and other vegetable material as possible. This material, often sown along with the seed, tends to rot and may encourage fungal diseases.”

For moist fruit, such as ripe tomato or cucumber, the seed is surrounded by mucilage. When the fruit is fully colored and ripe, scoop out these seeds and wash them in a fine sieve under running water to remove the mucilage. Allow them to dry in the shade.

“If the mucilage is difficult to dislodge, with a gloved hand gently rub the seed against the wire mesh screen of the sieve,” she said. “Once the mucilage is removed, place the seeds to dry in a single layer on absorbent newspaper in the shade. Turn over so both sides dry or dry both sides at the same time by suspending the seed between layers of mosquito netting.

“Label batches of seed to keep track of what is drying where.”

Pollard recommended the following guidelines for storing seed.

“Only clean and well-dried seed should be stored,” she said. “The two deadly enemies of stored seed are warmth and moisture. So, inspect the seed one last time before it is stored. Is it the very best you could collect? Is it clean, dry, and free of chaff and other debris?”

To keep stored seeds cool and dry, store them in clean, airtight containers or in small paper bags in the bottom drawer of your refrigerator. Paper bags, unlike plastic, allow the moisture to escape from the seed, so mold and rot is less likely. The cool refrigerator temperature slows down the natural respiration and deterioration of the seed. Clearly label the containers with the name of the plant and the date and place of its collection.

“How long seed last in storage depends on the type and quality of seed saved and the storage conditions,” Pollard said. “Some deterioration is inevitable. Aim to use all stored seed next year or within two or three seasons from the time of collection, as sprouting or germination rates will go down with time. In general, the lower the humidity and temperature in storage, the longer the viability of the stored seed.”