Written by Sheila Hillberry, SDSU Extension Master Gardener volunteer, under the direction and review of Prairey Walkling, Kristine Lang, and Rhoda Burrows.
After seed starting, or at the end of the growing season, many gardeners find themselves with partially full seed packets. Do not throw these seeds away, as most will last more than a year after the “sell by” date. Some seeds will keep 10 years (or more!) if carefully stored. Below are some recommendations for how to store your garden seeds to keep them viable for use again next season.
Seed Storage Tips
Here are some tips to extend the life of seeds:
- Reducing humidity is the most-important factor in extending the life of seeds. In general, relative humidity below 60% is best for seed storage. Avoid storing seeds in sheds or garages where they may be exposed to high humidity in the summer.
- Store your seeds in a cool, dry location away from direct sunlight. Exposure to temperatures above 90 degrees Fahrenheit will greatly decrease the viability of your seed for future planting seasons.
- Seeds can be stored in sealed containers, plastic bags, and wax or paper envelopes. When seeds are stored in sealed containers, ensure that moisture is not trapped within the container; if you see condensation forming inside the jar or container, you may have issues.
- A refrigerator can be a good option for seed storage that can extend the storage life by several years. Seeds stored in the refrigerator should be in a sealed container. When seeds are removed from cold storage, let the container reach room temperature before opening the container to avoid condensation on the seeds within the container.
- If you have grown and harvested seeds yourself, make sure that they are thoroughly dry before storing the saved seeds.
- If you want to check for viability before planting, do a germination test.
Expected Storage Life
Different seeds have different expected shelf life, even with the best conditions. Parsnips are notoriously short-lived seeds. Tomatoes, lettuce, beans and peas benefit most from careful handling. Keep in mind that the older the seed, the lower the germination and vigor. For this reason, some choose to mix in new seed with the old when direct seeding or seed at a higher rate to account for a reduced percentage of plants that may germinate after several years of storage. Time is precious in our South Dakota growing season, and no one wants to end up short on their favorite flowers or vegetables!
Seeds have greater longevity than you may think. With proper storage, you can often successfully utilize commercial seeds for several years beyond the “sell by” date. This allows you to save money by not purchasing new seed every year, and it also allows you to hang onto your favorite varieties in the event there are issues with availability in the following season. Below are the expected storage life of several popular vegetable seeds when stored properly.
Shelf Life by Variety
- Swiss chard
- Brussel sprouts
References and Resources
- Buttal, L. and S. Siegel. 2015. The Seed Garden: The Art and Practice of Seed Saving. Seeds Savers Exchange, Inc. Decorah, IA.
- Ells, J.E., L.N. Bass, and D. Whiting. 2020. Storing Vegetable and Flower Seeds. Colorado State University Extension.
- Gough, R. and C. Moore-Gough. 2011. The Complete Guide to Saving Seeds: 322 Vegetables, Herbs, Flowers, Fruits, Trees, and Shrubs. Storey Publishing. North Adams, MA.
- Steil, A. 2023. How to Store Seeds and Test Germination Rates. Iowa State University Extension and Outreach.