K-State Research and Extension

How Long Can Garden Seed Be Kept?
If you have garden seed left over from last year, or even previous years, you may wish to hang on to it to use this season. Most gardeners love to look over new varieties and pick out fresh seed with anticipation of a new year. New seed can be expensive, however, and you may not find the same variety that performed well the previous year. Thus, gardeners should consider using old seed if proper care has been taken in its storage.
Kansas State University’s Extension horticulturists generally consider most garden seeds will remain viable for about 3 years under cool, dark, dry, conditions though there are exceptions. For example, members of the carrot family (carrots, parsnips and parsley) are short-lived and are usually good for only 1 to 2 years.
Seed Longevity
Crop groups vary in seed longevity. Use the following university recommendations as a guide for seed stored under cool, dry conditions.
Crucifers (cabbage, cauliflower, broccoli): 4 to 5 years.
Corn: 2 to 3 years.
Lettuce, endive: 4 to 5 years.
Spinach, beets, carrots and chard: 2 to 3 years.
Cucurbits: Squash, melons (including watermelon): 4 to 5 years.
Tomatoes: 4 years.
Peppers: 2 years.
Onion, parsley, parsnip and salsify: 1 year.
Storing Seed for Next Year
To store this year’s leftover seed, try a zip-locked plastic bag or a plastic jar such as a reused peanut butter jar to keep seed dry. Seed will be viable longer if kept between 40 and 50 degrees F. Temperatures a bit lower than 40 degrees are fine as long as they are not sub-freezing. Therefore, a refrigerator is a better choice than a freezer which can prove detrimental to seed longevity if there is too much moisture in the seed.