URBANA, Ill. – While there may still be snow on the ground outside, it is never too early to start planning your garden for the spring. Begin by digging through your old seed packet stashes to find those still viable to plant.

Seeds are considered viable when they are capable of germination under suitable conditions. If stored properly, some seeds may remain viable for several years, while others are only viable for a short time. For example, parsley and onion seeds have a short viability time, while melons, cucumbers, and cabbage can last five or more years. A package of seed will be labeled with the year it was packaged. Most seeds should be used within three years.

“Performing a simple seed viability test to check the germination rate may save you from purchasing new seeds year after year,” says Brittnay Haag, horticulture educator with University of Illinois Extension. “Place 10 seeds on a damp (but not soaking wet) paper towel. Roll up the paper towel and store it in a closed plastic bag, labeled with the seed type and date, and place it in a warm (above 70 degrees Fahrenheit) location, like a sunny windowsill.”

Haag suggests checking every few days to see if any seeds have germinated. Once they begin to grow, count how many seeds have germinated to find the germination rate. If all the seeds have germinated, follow the seeding directions on the packet. If the germination rate is 70-90%, you will need to plant more than the recommended rate to replace those that may not germinate. If the germination rate is below 70%, Haag recommends purchasing new seeds.

Another way to test the seed viability of larger seeds like peas, beans, and corn is to place them in a bowl of water. “If they sink, they are still viable; if they float, they are garbage,” Haag says.

If stored properly, some seeds can last many years. Seeds need a cool (between 32 and 41 degrees), dry place, like a refrigerator. Seeds can be stored in paper envelopes or glass containers.

Once you test the viability of your seeds, enjoy flipping through seed catalogs to find new varieties to try this spring. Haag also suggests hosting a “seed swap” with friends (who also tested their seed viability) to share different varieties amongst each other.

After selecting your seeds, it is time to start thinking about a planting schedule. As a general rule of thumb, most annual plants should be started in flats indoors about six weeks before the last frost in your area. Do not start your seeds too early (especially tomatoes) or you run the risk of plants becoming too leggy before they can be planted outside. Check your seed packets for suggested planting methods.

Plants started indoors will need six to eight hours of direct sunlight. Grow lights can be used to supplement sunlight, if needed. About two weeks before planting outside, place the plants outdoors in a shady, wind-protected area during the day and bring them in at night. This will allow plants to get acclimated to the environment before being planted.

Haag says, “Spending some time sorting and organizing your seeds, testing the seed viability, or trading seeds with friends would be time well spent for any gardener!”

University of Illinois extension