Seed packages never have the correct amount of seeds. There are either not enough requiring more than one package or too many seeds. What should be done with the extra seed in a seed package? If too many seeds are planted in an area and all the seeds grow, they will need to be thinned. Extra seeds planted as bedding-out-plants results in excess seedlings. When extra seed is planted inside, there will be an excess of bedding-out-plants planted as bedding-out-plants that take up room inside and will eventually be thrown out, or given away.
Extra seeds can be given to others or kept for the next planting season depending on the variety. When keeping seeds, place them in a closed container out of direct sunlight it in a cool dry area of the house.
According to the University of California the rule of thumb for storing seed is that the temperature in Fahrenheit and the percent of humidity should add up to less than 100. An example being: If the room temperature is kept at 60˚F the humidity should be less than 40%. Dry seeds can also be frozen and left in the freezer for a number of years.
Over the years, seeds have been tested for longevity by various groups and they have come up with an average number of years that seeds can be stored before germination rates are too low to make the seed commercially viable.
The information on the following paragraphs have been gathered from various sources and the minimum number of years until germination rates fall has been used
Seed viability vegetable
1 year: Onion, parsnips, leeks chives and parsley; 2 years: Corn, okra, pepper, sage; 3 years: beans, broccoli, carrots, celery, kohlrabi, peas, spinach, fennel; 4 years: beet, cauliflower, eggplant, pumpkin, squash, Brussels sprouts, cabbage, Swiss chard, kale, rutabaga, tomato, turnip, watermelon; 5 years: muskmelon, radish, dill, cucumber, endive, collards, lettuce, basil, cilantro.
Seed viability flowers
1 year: Flax, heliotrope, larkspur, viola; 2 years: anthemis, clarkia, foxgloves, gaillardia, hollyhock, nigella, marigold, pansy, petunia, sunflowers, sweet pea, sweet william; 3 years: California poppies, cineraria, cosmos, godetia, snapdragons, 4 years: ageratum, celosia, lobelia, love-lies-bleeding, wallflower; 5 years: calendula, nasturtium, zinnia.
A home gardener has a few more options than commercial growers or companies that sell seed. They can use old seed, planting seeds closer together to insure a good germination. If it doesn’t germinate, it is quick to replant. Seedlings that grow to close together can be thinned.
Seed can easily be tested to check its viability, or germination rate. Count out a set number of seed and placing them on a wet paper towel or coffee filter. Fold the wet paper over the seeds and place it a plastic bag in a warm area. After the first couple of days, check the seeds daily for a week or two. The number of seeds germinated compared to how many seeds in total provides the percentage of viable seeds in the package.
Look at the percentage of seeds that germinated. Is it high enough to make it worthwhile planting the seed or is it better to purchase new seed. Always purchase new parsnip and onion seed as their germination rates decline sharply after one year.
Before purchasing this years seed, look at what is left from last year. If in doubt of the year purchased, test for germination rate and then decide what needs to be purchased. Be sure to store this spring’s excess seed in a cool dry area.
Linda Tomlinson is a horticulturalist that lives near Rocky Mountain House. She can be reached at email@example.com