Do you have a stash of old seed packets tucked away with your gardening gear, thrown on a shelf in the garage or mingling with this-and-that in a drawer? I bet you do. Do they hold the promise of healthy plants or are they past their prime?
Seed packets have a sell-by date, but depending on the seed type and the storage, they can be viable far longer.
According to Colorado State University, flower and vegetable seeds can be stored at room temperature for a year without significant loss of germination. Given optimal dry and cool conditions, some seeds can be viable for up to ten years. Colorado’s semi-arid climate is advantageous for seed saving as moisture shortens seed’s shelf life. This CSU publication contains details on seed saving, the longevity of common plant seeds and germination rates.
If you want to know if your past season’s seeds are worth planting, you can easily find out by doing a germination test. Count out 10, 20, or 30 seeds and spread them on several layers of moistened paper towels. Carefully roll them in the paper so the seeds stay separated. Place the roll in a plastic bag and store in a warm spot without direct sunlight, such as the top of the refrigerator.
Check your seeds for signs of sprouting after 2-3 days and daily after that for about two weeks, keeping the towels moist. After that time, divide the number of sprouted seeds by the number you started with and you have the germination rate. You’ll likely find that the rate is reduced, but the seed is still useful if you plant more seed than you need, using the germination rate as a planting guide.
If few seeds sprout, they are too old and not worth saving. By doing the test, you’ll avoid being disappointed by poorly performing plants in the garden.
February is a great time to take stock of your seed stash and purchase what you need for the year. And if you have some still-good seed you don’t want, consider sharing them with a gardening friend or donating them to a school or community garden.
Written by: Linda McDonnell, Denver County Master Gardener