Quick Guide: How To Do A Seed Viability Test

Have you collected a lot of seeds from your garden? Perhaps you found a stash of seeds from previous years and you’re wondering if they are still viable.

Before you spend your garden dollars on buying new seeds, or sowing those older seeds, there is a simple way of doing a seed viability test right in your kitchen. Use this test on the flower and vegetable seeds you’re starting this season.

seed viability test

Seeds Germinating by USFS Region 5 via CC BY-NC-SA 2.0

The water seed viability test

A quick and easy seed viability test that is often recommended is to see if your seeds float in water.

To perform a water test, take a mason jar or deep dish and fill it with water. Take the seeds you’re unsure of and pour them into the container with water. Let your seeds sit in the water for about 20 minutes. If the seed float they are likely to be poor germinators. However, if your seed sink to the bottom of the container, they should still be viable.

There are a couple of issues with this seed viability test, but it is a quick way of checking older seeds as you are planting. Keep in mind that sometimes seeds just float. So just because a seed doesn’t sink to the bottom doesn’t mean that you should toss them and not plant them in your garden. Go ahead and plant the floating seeds, too.

Paper towel seed viability test

My favorite method of checking on seed viability is to “plant” a few seeds in a moist paper towel and seeing how many germinate.

To get started you will need:

  • About 10 seeds to test
  • A paper towel or used coffee filter
  • Plastic sandwich bag
seeds germinating paper towel

Seeds germinating in paper by USDA via CC BY-NC-SA 2.0

Step 1:

Take your seeds and soak them as described in the water test above.

Step 2:

Moisten your paper towel. Don’t soak your towel, a few gentle mists from a spray bottle should suffice.

Step 3:

Place your soaked seeds inside of the paper towel. Space them about a quarter of an inch from each other.

Step 4:

Place the paper towel with the seeds inside the plastic sandwich bag and seal it. Lay your seeds and bag in a warm location away from direct sunlight.

Step 5:

After 2 days, check on your seeds and see if they have germinated. If the paper towel inside seems to be drying, carefully open it up and give it a couple of sprays from your spray bottle to keep the towel moist. Within 7-14 days all of your seeds should have sprouted.

Interpreting your seed viability test results

Since we only used 10 seeds for this test, figuring out the germination rate will be easy. If all 10 seeds germinated you have a 100% germination rate. If 9 seeds germinated, you have 90%. If 8 seeds germinated, you have 80%, and so on. Obviously, anything between 80%-100% is ideal. You can sow these seeds with confidence that they will germinate.

Anything lower than 50% means that your seeds are quickly losing viability. But that doesn’t mean you can’t sow them now. It just means that you need to sow more of them at once to make up for the seeds that are too old to germinate.

This is a quick and easy way to conduct a seed viability test from seeds you have collected from your garden, seeds you have traded or found, and seeds that you buy but are unsure of their quality. You can also conduct this seed viability test by planting the same number of seeds in soil. But if you get low germination rates, then you’ve just wasted valuable seed starting soil.

You might also enjoy our seed saving guide and our post on where to buy rare heirloom seeds.

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