Save Time and Emotional Labor by Testing Your Dusty Old Seeds

If you’re a gardener, chances are you’ve got some seeds squirreled away that are past their prime. Maybe you’re overzealous with your seed orders every year (me), couldn’t resist a bunch of free but expired seeds at a garden event (also me), or can’t bring yourself to throw away a packet with pretty illustrations on it (me again!). 

If this is you, too, I have good news: with a simple home science experiment, you can test the viability of your old seeds! Toss the seeds that fail the test with peace of mind and without wasting any potting mix or time staring anxiously at dirt. If they succeed, huzzah! Go ahead and sow them, and since they’ve already germinated, they have a fair chance at growing successfully.

This year I tested heirloom “Painted Lady” runner beans dated 2021 and dwarf “Sunspot” sunflowers from 2022 and now have small plants of each growing away. Read on for the VERY easy process.

What you’ll need

This experiment requires no special equipment. All you need is a plastic Ziploc bag, a paper towel, and the magic ingredient to life itself: water.

And, of course, some old ass seeds you’ve hung your hopes and dreams on.

How to conduct the test

Lay your seeds out on the paper towel and spritz generously with water, until the towel is uniformly damp. If you don’t have a spray bottle, you can also just wet the towel under the tap and gently squeeze out the excess before placing the seeds on top.

Fold the towel over or layer another towel on top and spritz/moisten again.

Place the damp envelope of seeds into the Ziploc bag. You don’t need to seal it but just let it fall closed.

Place the bag in a warm-ish place. Unless the seeds you’re testing need light to germinate, they can be tucked away in a cupboard above the stove or on top of the refrigerator. I left mine on a sunny tabletop. 

Important: be sure to explain the experiment to anyone who lives with you so that they don’t throw your seeds away. Last year I had to fish pepper seeds out of the trash because my husband did not understand what was going on. If you have kids in the house, they’ll probably think it’s pretty cool.

Over the next few days, don’t let the paper towel dry out, adding/spritzing more water as needed.

Look out for results

After day two or three, start checking the seeds for signs of life. How obsessively you check them is up to you. Once a day should suffice.

Germination times will vary, but in my experience, it happens quickly. The sunflower seeds germinated within three days, the runner beans in six. 

The cool thing about this test is that you get to witness the earliest stage of the germination process rather than waiting until the seedling pops above the surface of the soil. When the skin of the seed starts to split and little white roots peek out, you can rejoice!

Seeds are amazing. If stored properly, they can remain viable for years. These runner beans and sunflowers had likely not been stored in ideal conditions for the past two to three years, but a bunch germinated nonetheless!

Plant the winners

The viable seeds should be planted soon after germination so their roots can dig into some soil and send up shoots. Grab your seed starting mix or regular potting mix and plant the seeds at the depth indicated on the package.

Within a couple days, you should start to see green emerging from the soil. From here on out, just keep your miracle babies watered and fed as you would for any seedling.

My sunflowers are all doing well, but I had a little trouble with my runner beans. Though all the seeds I planted looked as though they were about to sprout on the surface of the soil, only one of them managed to send up a healthy seedling. That’s alright, I don’t have room for more than one anyway.

Can all seeds be tested this way?

I’m not a botanist. But I do know that the world of plants is vast. Some seeds take years to germinate, others take 24 hours; some need to be cold, others warm; some exposed to light, some kept in the dark. But most of the popular flowers and vegetables that gardeners grow from seed just need a combination of moisture and warmth, given consistently over a few days.

In addition to sunflowers and runner beans, I have successfully used this test with peppers, and I’ve seen folks do it with radishes and fava beans too. 

I will say that this test would be difficult with really tiny seeds. They would be harder to handle and see. With chunkier seeds, it’s a cinch.

Best of luck!

This process blissfully takes the guesswork out of starting seeds. When you plant a seed that’s passed the test, you know for certain that it has the capacity for growth.

Next time you find yourself weighing whether to throw away expired seeds or risk wasting valuable soil and space on giving them a go, try this handy test. Worst case, all your seeds are dead and you can toss them with a clear conscience. Best case — MORE PLANTS!