How to Check Seed Viability

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Most of the time when ordering seeds for a new growing season you will receive way more than you really need. This can cause you to sometimes have hundreds of seeds left over after planting.

If you have some vegetable seeds left over from previous seasons, you may be wondering if those old ones are still good to use for starting your new vegetable garden.

The germination rate drops as the seeds become older, so those that are three years old will have a lower germination rate than ones that were saved from last season.

Of course you could wait until Spring, plant them, then see what happens, but that’s a bit too risky. Fortunately, there is a very easy “test” you can perform to check to see if old seeds will grow, or are viable.

I posted a while back on how to pre-germinate vegetable seeds, and checking seed viability is basically the same thing. As a short refresher, I’ll go over the steps for checking seed viability.

Checking Seed Viability

Most vegetable seeds basically need two things in order to germinate – moisture and warmth (there are some lettuces that germinate better when there’s some light as well).

We can easily replicate those conditions and spark the seed into germination. Here’s what you will need:

  • Paper towels
  • Misting bottle filled with clean water
  • Old seeds to check
  • A Ziploc baggie
  • A warm location

Moisten a Paper Towel

First, lay a paper towel on a flat, clean surface and moisten it with the misting bottle. The paper towel doesn’t need to be sopping wet, just throughly moistened.

Lay Damp Paper Towel on a Counter or Table

Add Your Seeds and Wrap Them Up

Place five to ten old seeds in the center of the moistened paper towel and fold it to form a small square pouch.

Fold the Left and Right One-Thirds of the Paper Towel Over the Seeds

The Finished Seed Germinating Satchel

In the pictures above I am checking some old Lemon Cucumber seeds I had left over from a few years ago. You can see that some of the seeds are sitting on top of one another, but it’s best to separate them so they aren’t touching.

Place Seed Pouch In a Baggie

With the moistened seed pouch completed the next thing you need to do is place the pouch inside the sandwich baggie and seal it up.

Place the Seed Germinating Satchel in a Zipper Lock Sandwich Bag

Once the baggie is sealed you simply place it in a warm location (at least 75°F – 80°F).

Now all that’s left is to wait.

Checking the Old Seeds for Signs of Germination

Different seeds will have different lengths of germination. Check the seed packet you are using to determine how long it takes your particular seeds to germinate.

If you don’t have the seed packet to go by, here’s a handy seed germination chart.

After a couple days begin checking your seeds. They should begin swelling in size some. This means they have started the germination process.

After several days you should begin seeing tiny shoots appear from the seeds. This means they are germinating and are good to use! If after a couple weeks you don’t see any signs of germination then you can assume the seed is a dud.

The Tiny Shoots That Appear Coming From the Seed Means They Are Ready to Sow

Determining Germination Rates

If you check seed viability of ten seeds and only five germinate then you have a germination rate of about 50%. That means you will need to double the amount you sow in order to have enough plants.

In my opinion, if you check ten seeds and only two or three germinate it is a good idea to get new seeds unless it’s a rare or vintage variety of seed. It’s not worth the risk with that low of a germination rate.

It is also a good idea to perform this check right before you plan to sow the seeds – whether it’s indoors or out. Once the seeds begin germinating they need to be sowed or they may end up going bad.

Performing a seed viability check is a good way to check to see if your old seeds will germinate and also pre-germinate them to lessen the amount of time it takes them to germinate at planting time.

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Comments

  1. This is exactly what my mum used to do in order to start seeds off, she would put them in paper and then in the airing cupboard until they germinated. Thanks for reminding me what a great idea it is to do this.

  2. Hi Tee,

    I’ve seen this method of germinating seeds numerous times through growing up, do you think it’s a much more effective way of starting seeds off? In the past I’ve been shown a number of different techniques my old man showed me, whether it be in small pudding pots with loose soil in, or placed along the kitchen windows in small trays!

  3. This method can work well with all sorts of seeds. The key is working out (or reading online) the best methods for the plant or vegetable you want to grow.

  4. Thanks for your appreciation! I feel very strongly about the plight of our native bees and hope that this blog will help people identify them and want to help save them by growing nectar-rich plants in their gardens.

  5. This method can work well with all sorts of seeds. The key is working out (or reading online) the best methods for the plant or vegetable you want to grow.

  6. This handy little trick is something my Grandma taught me when I was a kid and used to plant seeds in her garden. Thanks for reminding me of it, useful tip and good memories :)

  7. Dianne Shaw says:

    I’Ike to join your newsletter and get a catalogue. I was trying Ti sign up and place an Oder, then it went away. Thank you for your help, Dianne

  8. Good tip:) There is nothing more disappointing that the long wait, and not a thing comes up. I usually try to use up seed by the expiration date printed on the packet, but have found that sometimes they last past that. It ought to be a crime to throw away good seed:)

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