Testing seeds that you save from your own garden or find in the back of your junk drawer can save you time and prevent you from wasting garden space and resources. If you’re giving seed to a seed share or a seed library, it’s important that you know the seeds you’re sharing are viable, so as not to discourage anyone from gardening or participating in community seed efforts in the future. This germination testing method is the same method used by large and commercial seed companies.
This method will work for most seeds, but some seeds require special preparation before being planted such as soaking or chilling (vernalization or stratification). Before performing a germination test, get to know the seed to ensure you’re offering an optimal environment for it to grow. All seeds need to stay moist and warm (>55°F) to germinate.
**Can also use soil, be mindful to sterilize your transplant trays before seeding to prevent contamination of pathogens**
Spray bottle with water
Rip 2-4 sheets of paper towel, enough to hold your seeds and fold a sheet to cover them
On your Ziploc bag write the seed variety, amount of seeds, source of seeds, and the date with your permanent marker
Record the same information in your garden notebook
Spray the paper towel to moisten, be careful not to soak it. The moist paper towel will stick to the table and the seeds to prevent them from rolling out of place
Start to line up your seeds in a grid, leaving 1 inch from the edges of the paper towel. Leave ½ – 1 ½ inches between your seeds, depending on the seed size.
Once the seeds are placed, accordion fold the paper towel over the seeds and press on the edges, or place another paper towel over the seeds and spray it with water.
Slide the paper towel and seeds into the bag, close it, and store in a dark and not overly heated space.
Most seeds will germinate within 3-10 days. Check on your seeds daily and make sure they are staying moist. Take them out of the bag and mist the paper towel if needed.
Some seeds may not be viable and won’t germinate, others may get mold and should be removed from the bag immediately to prevent other seeds from getting moldy too.
Only count the seeds that show healthy germination, resulting in a few roots and a main radicle.
Determining Germination Percentage
Divide the amount of successful germinations by the total amount of seed tested, then multiply by 100. For example, if you started with 25 seeds, and 23 germinated, you would have a 92% germination rate
(Healthy seedlings / Total seeds) x 100
If you want to plant the young seedlings, Seed Savers Exchange recommends cutting the paper towel around the root body and then planting in soil. Keep indoors until strong enough for the outdoor environment.
Seed Savers Exchange. Home Germination Test. Retrieved from https://www.seedsavers.org/site/pdf/HomeGermTests_LAFrevised.pdf