Seed Germination Using the Paper Towel Method

When gardening, few things can be more frustrating than having seeds that just won’t sprout. Whenever I’m faced with this problem, the first thing I always check is the viability of the seeds themselves. Seeds, when stored improperly or for too long, can lose their ability to grow. If you’re having trouble, a very easy way to test seed germination is by using the paper towel method.

Generally speaking, seeds need three things in order to germinate: water, oxygen, and proper temperatures. With the paper towel method, you can create a favorable environment for seed germination with these three elements. You'll just need a few paper towels, a large zip-lock bag, and some water. Note that there are actually towels specifically designed for this purpose, but I haven't used them and don't think they are necessary.

Step-by-step guide to the paper towel germination test

1. Gather your supplies.
2. Lightly moisten a paper towel with water. It should be noticeably damp, but not soaking wet.
3. Take your seeds and place them on the damp towel, leaving 1–2 inches of space between each seed. 10–20 seeds should be sufficient for a standard test.
4. Take another moistened paper towel and gently lay it on top of the first towel—be careful not to disturb the seeds.
5. Finally, slide the paper towels into a Ziplock bag, but don't close the bag. Leave it fully open so the seeds get the oxygen they need.
6. Place the bag in a warm place indoors. Near a window should suffice, but if you have a heated seed germination mat, all the better. You’ve basically just made a mini greenhouse in a plastic bag!

Maintaining optimal conditions for seed germination

While waiting for the seeds to germinate, be mindful of maintaining proper conditions. Keep the towels moistened with the proper amount of water. Don't let them dry out, but don't soak them too much either. Keep the seeds in a warm place, but out of direct sunlight.

Most seeds do not need much light to germinate. In, fact too much sun can inhibit germination, and don’t forget to keep the bag unsealed. You’ll see a small amount of humidity forming inside and this is a good sign that the ideal conditions are being created.

Within a few days, if the seeds are viable you should be able to see signs of germination. This can look different depending on what kind of seeds you are testing, but generally you will see a small shoot sprouting out of the seed. This is called the embryo, and it is the part of the seed that develops into the full plant.

At this point you can start to determine your germination percentage. If most of your seeds have started to sprout, then that batch of seeds should be fine to plant. If only half of them have shown signs of germination, then they may still be fine to plant, but I’d recommend sowing extra to compensate for the lower germination rate.

What happens if no seeds show any signs of germination? This means that somewhere along the way, the seeds lost their viability. It's possible that they're either old or were stored in a spot that wasn't cool enough (35-40°F is ideal). Or maybe you harvested the seeds yourself from one of your plants last year, but the conditions weren’t ideal. Whatever may have happened, it’s best to discard the unviable seeds and move on.

Moving the germinated seeds

If you do have seeds that germinated in your paper towel test, you can actually transplant them for use in your garden. Just make sure to plant them not long after you see signs of sprouting. If you wait too long, the seeds will either start to show signs of molding or the roots will actually grow too long and become tangled with the fibers of the paper towel itself. Since it's still a little too chilly outside in early Spring, I've transplanted my sprouted seeds in peat plugs as an interim step before I move them to my balcony garden.

Treat the young sprouts with care like you would any other plant you're transplanting, making sure not to damage or overwater the fragile sprouts. Now that you know the germination rate of your seeds, you can plan accordingly and be able to rule out seed viability as a source of any problems you might be having.