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.
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.
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.
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.
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.