A packet of vegetable seeds may look dry, brittle, and lifeless, but old seeds are very much alive in many cases. Inside each plant seed is the embryo of a future plant. However, seeds do not remain alive forever and will expire. How long seeds last depends on the type of seed and how well it is stored. Read on to learn how you can tell if old seeds are still good based on a sprouting test and look at how some seed types last on average.
Most Vegetable Seeds Can Stay Viable for Years
Most vegetable seeds remain good for about two to three years, but some, such as onions, deteriorate within a year. Lettuce, on the other hand, can successfully sprout after five years. The best way to store seeds is to make sure they are dry, then store them in an airtight container, and keep the seeds at a consistently cool temperature.
The table below lists average years of viability for well-stored vegetable seeds, compiled from regional sources. There will be some variability because of the variety of seeds and whether the seed was fully ripe and kept dry in storage.
How Long Do Seeds Last?
|Vegetable||Storage Years||Vegetable||Storage Years|
How to Store Vegetable Seeds
You can't do anything to change the life expectancy of different types of seeds. But if you save your own seeds or need to store purchased seed, you can keep them fresh for the maximum amount of time by taking these steps to store them properly:
- Be sure the seeds are completely dry, to the point of being brittle before you pack them away.
- Place dried seeds in a paper envelope to absorb any moisture that might get in, and label with the name and year.
- Keep the envelopes in an airtight container.
- Store them in a cool, dry, and dark place.
Although you can use Ziploc or zip-close baggies, they are not the best option; paper envelopes are best since any trapped moisture can escape. If any seeds still have moisture, they may cause all the seeds in the bag to get moldy and spoil.
How long seeds last in the freezer is highly dependent on the seeds being thoroughly dried before freezing. Moist seeds can crack or split when frozen, destroying the embryo. Adequately stored seeds can last 10 years or more in the freezer. And some seeds rely on a freezing and thaw cycle before sprouting.
Spouting Test for Seed Viability
There's an easy way to determine if your saved seed is still good and what percentage of it you can expect to germinate.
Equipment / Tools
- Permanent marker
- 10 seeds
- Paper towels
- Sealable plastic bag
Wet Paper Towel
Moisten a sheet of paper towel so that it's uniformly damp but not dripping wet.
Place the 10 seeds in a row along the damp paper towel.
Roll or fold the paper towel around the seeds so that they are covered.
Seal and Label Seeds
Place the paper towel with the seeds into the plastic bag and seal it. Write the date on the plastic bag, so there’s no guesswork involved. If you are testing more than one type of seed, label the bag with the seed type and variety.
Let the Seeds Sit
Place the plastic bag somewhere warm, about 70 degrees Fahrenheit (a sunny windowsill or top of the refrigerator should work).
Check Towel Daily
Check daily to be sure the paper towel does not dry out. It shouldn’t because it is sealed, but if it gets very warm, you may need to re-moisten the towel with a spray bottle.
Watch for Germination
Start checking for germination in about five days. To do this, gently unroll the paper towel. You may even be able to see sprouting through the rolled towel. Very often, the roots will grow right through it.
Check Seed Packet
Check your seed packet for average germination times for your particular seed, but generally, 7 to 10 days should be enough time for the test.
After 10 days, unroll the paper towel and count how many seeds have sprouted. This count will give you the percentage of germination you can expect from the remaining seeds in the packet. If only three sprouted, it is a 30 percent germination rate. Seven would be a 70 percent germination rate; nine would be a 90 percent germination rate, and so on.
What the Germination Rate Tells You
Realistically, if less than 70 percent of your test seed germinated, you would be better off starting with fresh seed.
If 70 to 90 percent germinated, the seed should be fine to use, but you should sow it a little thicker than you usually would.
If 100 percent germinated, your seed is viable, and you’re ready to plant.
Do not waste the seeds that have germinated in your test; you can plant them. Handle them carefully, so you don’t break the roots or growing tip. Don’t let them dry out. It’s often easiest to just cut the paper towel between seeds and plant the seed, towel and all. If the root has grown through the towel, it is almost impossible to separate them without breaking the root. The paper towel will rot quickly enough and, in the meantime, it will help hold moisture near the roots.
Storing vegetable and flower seeds. Colorado State University Extension.