How to Check for Seed Viability

  • By: Sandra
  • Date: March 18, 2022
  • Time to read: 3 min.

Like many gardening gurus you probably store away past years’ seeds at the end of every season. Even though expiration dates say it’s okay to use the particular seed, you have doubts. For many reasons it could have lost its ability to germinate and you want to know whether this really is the case to save some headaches in advance. If you are unsure whether your old seeds will sprout and you don’t want to wait for them to grow to find out, you can perform a seed viability test. It is very easy and efficient. Here it goes.

Things you will need:

Clean coffee filter or paper towels
Clean zipper bag or sandwich bag
Sunny window

The test

Take a clean paper towel or coffee filter. Moisten it. Place 10 or 20 seeds onto it (10 is better). Fold the seeds. If you use exactly ten seeds, you will find it much better to calculate the percentage of germination after that. Here is why. If 5 out of 10 seeds germinate, then 50% of your seeds will grow during the season. That’s pretty risky. So you need more than 70% or else planting will not be worth the effort. Ideally, 8 or 9 out of 10 seeds will sprout. However, if you get less than 70%, you had better not put work into it at all. Buy new seeds for the upcoming planting season.
Now, let’s get back to the topic. We reached a point where you fold the seeds. Then place them in a sandwich/zipper bag and zip most of the way. Ideally, you will leave some room for the seeds to be able to breath. If you want to test out several different seeds, write down the name of the plant on each bag to avoid errors when identifying the seeds. Store the bag with seeds at room temperature (about 70 degrees Fahrenheit/21 degrees Celsius). Perhaps it is best to place it by a sunny window. Wait seven to ten days. During this time, make sure to keep the paper towel/coffee filter moist.
Next, when the time has elapsed, go back to your seeds. Unzip the bag and unfold the paper towel. Start counting to see how many seeds have germinated. If they are more than seven, you are in luck. Those seeds are viable. If not, you had better get rid of them and use seeds from the store.
If you get between 70% to 90%, it is okay to use those seeds. Just make sure to sow them thickly. Repeat the viability test for as many seeds as you want to test out.
Here is more information about some of the seeds.

Life expectancy of some seeds:

Up to one year: salsify, parsley, onion, parsnip
Up to two years: pepper, sweet corn, okra, leeks
Up to three years: peas, asparagus, Kohlabi, celery, carrots, broccoli. Spinach, Chinese cabbage, celeria, beans
Up to four years: watermelon, turnip, mustard, chicory, cauliflower, Brussel sprouts, beets, pumpkin, kale, eggplant, squash, Swiss chard, tomato, rutabaga, fennel
Up to five years: radish, endive, cucumber, muskmelon, collards
Up to six years: lettuce
As you can see, if you have been storing some lettuce seeds for three years, you can still use them. However, if in doubt, a simple viable test will shed more light on the issue. Plus, it will save money and effort.
So that’s pretty much it. Put those old seeds to the test and see if planting them is worth the effort. You can never go wrong with this seed viability test. Hope it works well for you. Enjoy planting!