Garden Blog

Seed Germination Testing

Storing seed properly helps increase the germination rate and the life of the seed.

“I have great faith in a seed. Convince me that you have a seed there,
and I am prepared to expect wonders.”
– Henry David Thoreau

Sow True tests all our seed types each year to make sure the germination rates are up to the standards set by the Federal Seed Act

Most gardeners have experienced the disappointment of sowing seeds that did not come up. It’s discouraging. What happened, you wonder? Too cold, too hot, too dry, too wet, the soil wasn’t right? Sometimes it’s the seeds. They may have been too old or were not stored properly.

Sow True tests all our seed types each year to make sure the germination rates are up to the standards set by the Federal Seed Act. This law, first enacted in 1939, was created to ensure accurate labeling and purity standards for seeds in commerce.

The germination rate tells you how many seeds of a particular seedlot are likely to germinate. It is usually written as a percentage, for example an 85% germination rate indicates that about 85 out of 100 seeds will germinate under proper conditions. Each type of seed has it’s own germ rate standard. It varies from 40% for New Zealand spinach to 80% for cucumbers.

At Sow True Seed we do germination testing three times a year to ensure high standards. We use our State testing labs to ensure we have expert and independent testing for all our seeds (we send batches of 200 randomly sampled seeds).

However, as a home seed saver, you can easily do germination testing in your home.You may want to do this if the seeds have been stored sub-optimally, the seeds are getting old (more than a few seasons), the seeds are from an unknown source, or you have saved your own seeds and want to share them with confidence!

Home Germination Testing Techniques

It’s a low tech operation. You can do the test with a paper towel inside a plastic sandwich bag. Dampen the towel and lay some seeds on it spaced evenly. You don’t have to test 200, 10 -20 will do. Slide it in the bag. Label the bag with the name and date. Put it in a warm, darkish place, leaving the bag partially open. Check it every day or so, moistening as needed. After 14 days, record your results and discard. If all the seeds sprouted you’ve got 100% germ! Less than that and you’ll have to do some math to figure your percentage. If some seeds sprout but have a low germ rate you can still plant them, just plant more to make up for it.

Sow True Seed takes germ rates and seed storage very seriously. We want to do all we can to make sure your seeds grow! We’re always happy to share our most recent germination rates.

Federal Germination Rate Standards


Asparagus 70
Bean, Garden 70
Bean, Runner 75
Beet 65
Broccoli 75
Brussels Sprouts 70
Cabbage 75
Cardoon 60
Carrot 55
Cauliflower 75
Celery 55
Chard, Swiss 65
Chives 50
Collards 80
Corn, Sweet 75
Cowpea 75
Cucumber 80
Dill 60
Eggplant 60
Kale 75
Kohlrabi 75
Leek 60
Lettuce 80
Melon 75
Mustard, Spinach 75
Okra 50
Onion 70
Pak-Choi 75
Parsley 60
Parsnip 60
Pea 80
Pepper 55
Pumpkin 75
Radish 75
Rutabaga 75
Savory, Summer 55
Sorrel 65
Soybean 75
Spinach 60
Spinach, New Zealand 40
Squash 75
Tomato 75
Tomato, Husk 50
Turnip 80
Watermelon 70

[59 FR 64491, Dec. 14, 1991]


Article Written by: Angie Lavezzo

About the Author: Angie Lavezzo is the former general manager of Sow True Seed. Beyond her professional role at Sow True, Angie's passion for gardening extends into personal hands-on experience, fostering plants and reaping bountiful harvests.