I was looking over my leftover packets of seed and noticed the following stamped on the packets: packed for 2022, sell by 2022-10-31. Does this mean that these seeds will have expired by planting time next spring and no longer be good to use?
— Justin Hanou, Northbrook
The seeds that you purchased this year should be just fine for you to use next year if properly stored. Many commercial seed packets will have similar wording on them, suggesting a “use by” date to help ensure that customers will get a good percentage of germination from the seeds they have purchased.
Store seed packets in a cool, dry cabinet. (RJ Carlson/Chicago Botanic Garden)
Many seeds will remain viable for several years past the “sell by” date on the packet. Seeds do not spoil like food does, but the germination rate of the seed will decline over time. The rate of this decline in germination will depend on the species of the plant. Many types of seeds, though not all, will store well for three years and maintain a decent percentage of germination. If your seeds are older, then sow more of them with the expectation that the percentage of germination will be reduced.
The proper storage of seeds is very important and relatively simple. Keep them in a cool and dry place until you are ready to sow them. A basement cabinet will work for many gardeners. The seed should be protected from freezing. Mice will eat the seeds so you will need to keep the seeds in a protected cabinet. Avoid storing the seeds in locations that are warm and moist. If you decide to put the seeds in a sealed plastic container, then include a desiccant packet or a packet of dry rice to help keep the seeds dry. The following list is how long common seeds can be used past their expiration if stored properly.
One year: Onion, leek, parsnip and parsley seeds.
Two years: Okra, pepper, sweet corn and spinach seeds.
Three years: Arugula, green bean, lima bean, broccoli, carrot, lettuce and pea seeds.
Four years: Beet, kohlrabi, Brussels sprouts, cabbage, cauliflower, Swiss chard, eggplant, tomato, kale, collard, mustard and rutabaga seeds.
Five years: Celery, bok choy, endive, melon, turnip, radish and watermelon seeds.
Six years: Pumpkin, summer or winter squash and cucumber seeds.
For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.