How to Perform a Seed Germination Test

Got some old seeds sitting around, and not sure if they will still grow? Here’s how to perform a simple seed germination test to make sure your seeds are still viable before planting.

Are your seeds from 2 years ago still okay to plant?

That’s a tricky question, as seed life can depend on a number of different factors – from seed variety, to how and where the seed was stored. In general, however, most seeds will keep just fine in a cool, dry place for at least 2-5 years. There are a few exceptions – such as corn, spinach, and onions, which may only last a year or two. (Here is a quick list of seed life expectancy which may be helpful: )

However, if your seeds are a few years old, it’s still a good idea to test them before spending all the time and energy of planting and waiting for day or weeks, only to have your seedlings fail to appear.

Whether you saved your own seeds and forgot to label them, or you have some old purchased seed packets from previous years and are wondering if they will still grow, there are many reasons why you may want to perform a seed germination test before planting.

Luckily, this is an easy process, as the article below demonstrates.

The testing method is simple.  You wrap up a random sampling of the questionable seeds in a wet paper towel, place the paper towel inside a plastic container, keep it out of direct light, and wait. The test should last as long as it usually takes good, new seed to germinate.  So, if you normally expect tomato seeds to germinate in 5-10 days – your test for old tomato seeds should be 10 days long.

As the seeds begin to germinate, you should check the seeds daily and keep a running scorecard.  Record the number of seeds that germinate successfully, and the number of seeds that fail or mold.  Each time a seed germinates or molds, remove it from the test (take it off of the paper towel).  At the end of the test, determine the percentage of seeds that germinated successfully, and extrapolate that percentage to the total number of seeds you have.

Here is a guide, with pictures, from the Southern Exposure Seed Exchange: How to Test Germination

And here is a more detailed approach from the Seed Savers Exchange: Home Germination Testing

For starting seeds in trays – this test should help inform your decisions about how many seeds you need to start.  For direct-seeding – this test should help you determine how densely to seed your garden bed.


Keep in mind that you need to do this test before it’s time to start the seeds in question.  For some seeds, the time it takes them to germinate in the test is the same amount of time that it will take them to germinate in trays, seed starting cells, or directly in the soil.  So if you usually expect 7 days for seed emergence for tomatoes, you should do your germination test at least 7 days ahead of the date when you plan to actually start the seeds.

For more info, check out the full article at the


Rose S.

An avid gardener since childhood, I love sharing my passion for gardening with others! I have gardened in a number of different climates and settings, from large fenced garden plots, to tiny patio and container gardens, and I firmly believe that everyone can learn to grow at least some of their own food - no matter where you live. Growing your own food can help you take control of your own health and food supply, and there has never been a better time to get started!

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