Germination testing your seeds

As seeds age, their ability to grow is reduced, and eventually, they become unviable and will not sprout/grow at all. The long term viability of seeds is dependent on the variety as well as the conditions they are stored in. Seeds should be stored out of direct sunlight in a cool, constant temperature setting like a refrigerator. Freezing them will maintain viability for much longer. This isn’t always possible, so testing your seeds for viability is essential to a healthy garden. A germination test (sprout test) is a true test of seed viability at any age.

Germination testing requires a few simple things, a wet paper towel, plastic sealable baggie and some seeds to test.
Moisten the paper towel and wring out as much water as you can, it needs to be moist but not soaked. Fold a couple of times to make it double thick. Sprinkle seeds to be tested onto one side and fold the other over the top. With the moist paper towel covering the seeds place into a sealable baggie and place somewhere warm. Check every 24 hours for tiny root sprouts to start growing from the seeds. If the seeds sprout, they can be planted or discarded. If planting, do not let the sprout get too big and plant as the sprout is still small, careful not to touch or damage the sprout.

Different seeds will require different sprout times with most viable seeds sprouting within ten days (double for carrots and a few other vegetables).
Checking every 24 hours will indicate when your seeds sprout and if after ten days they have not sprouted, the seeds are likely not viable and will not grow. After ten days take the number of seeds that sprouted, divided by the total number of seeds tried and multiplied by 100%. The resulting number is your germination rate for your particular seeds.
If you place ten seeds on the paper towel and six sprout, then 6/10×100% = 60% germination; if you start five and all five sprout, then 5/5×100% = 100% germination rate.

Germination rates that are too low or near 0% will require you to get new seeds. The germination rate will also indicate additional seeds you may need to plant to compensate for unviable ones. If you have a 50% germination rate, you should double up on seeds planted to get the number of grown plants you want. If you have an 80% germination rate, you will need an additional 20% seeds to give you 100% of the plants you want.

Some seed suppliers mark the germination rate on their website or even on packets of seeds, these numbers are for new seeds and will lessen with time.

Using a seedling heat mat will speed up the sprouting time dramatically for some seeds. I have had cucumber seeds sprout and planted in three days. The initial sprout is a root sprout, so when planting it should go down or at least horizontal and then lightly covered with soil.

Seed viability in years for some common seeds kept in favourable conditions;
Bean – 3; beets – 4; carrot – 3; swiss chard – 4; cucumber – 5; kohlrabi – 3; lettuce – 6; peas – 3; pepper – 2; pumpkin/squash – 4; rutabaga – 4; tomato – 4.

Gardeners note; Tomatoes and peppers can be started inside now and over the coming month to allow for a full growing season. Visit for more information;

Look for upcoming introduction to gardening courses and training at the Nipigon Legion Thursday and Saturday evenings when the current lockdown restrictions are lifted. In interested email


Square Foot Gardening Section



myBackyard is for recreational purposes only. Plants, mushrooms and berries cannot be 100% identified through this website alone. It is up to the reader to properly identify plants, fungi and trees. Some wild plants, berries and mushrooms are poisonous or can have serious adverse health effects. Even those listed as edible may cause adverse reactions in individuals. participates in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to,, and affiliated sites. As an Amazon Associate, we earn from qualifying purchases through our links.

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