If stored properly, open packages of unused seeds can be saved for later planting.
Leftover seeds are often stored in a drawer or other area where they are unprotected from heat and moisture. Under those conditions, the metabolic processes within the seeds speed up and cause rapid deterioration. Proper storage in cool, dry conditions slows down metabolic activity helping to ensure seed viability until planting time.
The best place to store seeds at home is in the refrigerator or freezer. Before placing them in the refrigerator/freezer, put the seeds (in packets or loose) in a sealed container such as an airtight plastic canister, jar, or freezer bag. Under these conditions, they are safe from the detrimental effects of heat and moisture.
Seeds and seed packets must be dry when stored, otherwise, they will provide a source of moisture during storage. Moist seeds in a sealed container will deteriorate even faster than dry ones that are left in unprotected storage. Two teaspoons of powdered milk or silica gel added to the containers of seeds will absorb any excess moisture. These materials may be packaged in a small piece of thin fabric. It is best not to use dry milk or silica gel when storing seeds of corn, okra, or beans, as over drying may result.
When stored under cool, dry conditions, seeds should remain viable for at least the following number of years from the time of harvest (not time of purchase):
| VEGETABLE | YEARS | VEGETABLE | YEARS |
| Asparagus | 3 | Lettuce | 5 |
| Beans | 3 | Mustard | 4 |
| Beets | 4 | Okra | 3 |
| Blackeye peas | 3 | Onion | 1 |
| Broccoli | 4 | Parsley | 1-2 |
| Brussel sprouts | 4 | Parsnips | 1-2 |
| Cabbage | 4 | Peas | 3 |
| Cantaloupe | 5 | Peppers | 3 |
| Carrots | 3 | Pumpkin | 4 |
| Cauliflower | 4 | Radish | 4 |
| Celery | 5 | Rutabaga | 4 |
| Collards | 4 | Spinach | 4 |
| Corn | 1-2 | Squash | 4 |
| Cucumber | 5 | Swiss chard | 4 |
| Eggplant | 5 | Tomato | 3 |
| Endive | 5 | Turnip | 4 |
| Kale | 4 | Watermelon | 5 |
| Kohlrabi | 4 |
To test questionable seeds, run a germination test. A few weeks before planting, sandwich 10 seeds in a paper towel and keep it moist (not wet). If at least 7 seeds sprout, the seeds are approximately the same as new seeds.
References: The Complete Tightwad Gazette by Amy Dacyczyn, page 443; Southern Living magazine; Pennsylvania Cooperative Extension Service Circular 562