When preparing for the upcoming planting season, you may be wondering how long do seeds last? Are your old seeds still good? Here are a few tips for estimating how long your seeds will stay viable…

Seed-starting season is just a few weeks away, and you may be getting your indoor seed starting supplies in order and doing an inventory to see what seeds you need to order this year.

Whether you’ve saved your own seeds from last year’s crop of your favorite variety, or you have a basket of seeds you have purchased in previous years, you may be wondering how long your seeds will stay viable. It’s so disappointing to plant a bunch of seeds, tend to them for days or even weeks, and see only a few come up – or even worse, none at all. However, you may be pleasantly surprised to discover how long your seeds last when stored properly – many of them for years beyond their recommended use-by date.

Here are a few factors that will help determine how long your seeds will last, according to SuperSeeds.com:

1. Age — All seeds are viable for at least a year, with many others viable for definitely two years. After that, the seeds germination rate may start to drop off. It’s not to say that these are not viable seeds that won’t grow into healthy plants. They will. You just may need to sow more seeds than you think, as all will not germinate. See this link for an easy way to test your seed’s viability.
2. Variety/Type of seed — Certain varieties of plants have a shorter seed life by nature and are best used within one year. Examples of some short-lived seeds are: asters, delphinium, leeks, onions, parsley, parsnip, and phlox. While other plants have quite a long shelf life, like: basil, beets, Brussels sprouts, cabbage, chard, cucumbers, kale, lettuce, pumpkin, radish, squash, tomatoes and zinnias. Even within the same vegetable, you may encounter different germination rates for different varieties. Pelleted seed is best used within one year, as the pelleting process can reduce the seed’s longevity.
3. Storage — Now this is key! Saving your seed properly is the first step towards your best germination success for next growing season. Unused seeds should be stored in a cool, dry location (ideal temperature of 50ºF at 50 percent humidity). Any exposure to heat, sun, or humidity can greatly lessen the seed’s viability. For home gardeners, your best storage bet is to put your seeds in a sealed glass container (must be moisture-proof) and store in your freezer or refrigerator. You can even tuck some rice in the bottom of your seed jars to help wick away any potential moisture. Properly stored seed can outlive their estimated viability by many, many years. A quick note: when taking your seed jars out of the refrigerator, allow them to come to room temperature before opening. This helps keep any potential condensation from forming.

However, even if all of these conditions are optimal and your seeds are still technically viable, some types of vegetable seeds will have certain requirements in order to germinate properly. These include:

• Light — Some seeds need light to germinate, while others need dark.
• Pre-soaking and Scarification — Some seeds have tough outer seed coats that can make it tough for the seedling to break through. To soften that outer cover, you can presoak the seed overnight. You can also use sandpaper or a knife to gently scratch the seed coat, scarifying it, basically creating an opening for the seedling to emerge through.
• Cold Treatment — Some seeds need to be exposed to a period of cold prior to being able to germinate. How cold and for how long all depends on the plant, but most can just be placed in the refrigerator for a few weeks prior to sowing.

If you’re not sure whether your seeds are still good or not, take a few and perform a germination test just to make sure before you sow a bunch of them – especially if your seeds are a bit older.

You can also visit SuperSeeds.com for a handy list showing the approximate life span of a number of flower, vegetable, and herb seeds – when stored properly. Keep in mind that these are just estimates, and your seeds may last longer or shorter than the time frames shown. (I’ve had corn and okra seeds stay good for at least 4 years, for example, but my pepper seeds never seem to keep beyond 3.) Be sure to perform a germination test on seeds you are unsure of before planting.