Germination testing at home

Posted by Anne Fletcher on

Most of the time as a home gardener, you don't really need to germination test your seeds.  You sow them and if they germinate, they're good.  Yay!

But sometimes you'd like to know if that old packet of seeds you just found is any good (perhaps before you share some with your friends . . .).

Here's how to test your seeds!


Start with a moist paper towel and arrange 100 seeds in a 10 x 10 grid.  This is super fiddly.  Even if you don't need reading glasses yet . . . you probably need some reading glasses.

Label your paper towel with the seed variety you're testing.

Picture of arugula seeds for a seed-starting germination test

Then, neatly fold up your paper towel, put it in a plastic bag, and leave it somewhere warm for about 10 days.

Picture of arugula, beets, and tatsoi seeds in a seed starting germination test

I did three varieties all at once for this test.


After 10 days, you can check the results!

Look at all the roots growing out through the paper towel!

Seed starting germination test results

Open up the paper towel and carefully, carefully check how many of the seeds germinated.  With luck, most of them will have germinated, and it will be easier to count the ungerminated seeds.

Arugula seeds result of seed starting germination test

Again, you're going to want your glasses!

In fact, if you have a microscope, even better!

looking at results of seed starting germination test under a microscope

One of the arugula seeds looked like it hadn't germinated, but when I got it under the microscope, I could see the teeny root just poking out.

Here's another fun thing to look at up close:

beet seed germinating with three embryos as part of the results of the seed starting germination test
This is a beet seed, with THREE roots!  How cool is that?  Beets and chard both have multiple seeds within each "seed."  


Now comes the math.  Are you ready for this?!  JK, it's super easy.
Just count how many seeds germinated and because you started with 100 seeds, that's your germination percentage.  With the arugula I got 100 out of 100 seeds for 100%.  The beets and tatsoi were both 93 out of 100, for 93%.
Most seeds last for many years, especially if they're stored in a dark, cool, low humidity environment.  So even if you have a packet of seeds from 10 years ago, you can test them to see if they're still viable!
Typically professional seed tests use 200 - 400 seeds to get a better sampling of a batch.  For home testing purposes you could use as few as 10 or 20.  Or just sow them and see what happens!

To summarize how to germinate test your seeds:

  1. Lay out 100 seeds neatly on a damp paper towel.  Fold it up, put it in a plastic bag, and leave it in a warm place for 10 days.
  2. After 10 days, count how many seeds germinated.
  3. The number of seeds that germinated divided by the total number of seeds tested is your germination percentage! 

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