Wondering if the seeds you saved from last year are still viable? This simple guide will show you how to test seed germination at home, ensuring a successful garden season ahead.
Have some seeds you saved last year but aren’t sure if they’re still good? Or maybe you have some older seeds tucked away? Here’s how you can test their germination to know what to plant and how much to plant for a successful garden this year.
I remember back in elementary school when we used to take bean seeds, wrap them in a damp paper towel, and place them in a jar, eagerly watching them grow. We observed each stage of development, from seed to sprout, witnessing the miracle of life unfolding right before our eyes.
It was truly a marvel.
God’s creation is amazing, isn’t it?
Little did I know at the tender age of nine, we were actually testing those seeds for germination. In fact, it wasn’t until I was in middle school that I learned what “germination” even meant. And honestly, it didn’t hold much significance for me back then.
But now, as I cherish the seeds we’ve saved from last year, I wonder—will they still grow? The answer is uncertain, but there’s a way to find out. You can check if they’re still viable, or if it’s time to order new seeds, with a simple test. And yes, it’s just like what we did in third grade!
Germination Tests to Check the Viability of Your Seeds
The Paper Towel Germination Test
Just like in those school days, the simplest way to test most seeds is with a paper towel. While not all seeds can be tested this way, many can. I always involve my girls in this process—it’s a fun addition to our homeschool adventures.
Here’s how to do it:
- Grab some paper towels. Write the seed type and date on the top of the towel with a marker.
- Dampen the paper towel with a spray bottle. It should be wet but not dripping—too much water might cause the seeds to mold, especially those in the cucurbit family.
- Take 5-10 seeds (if you can spare them) and line them about an inch from the top of the paper towel, spacing them about an inch apart.
- Fold the towel in half over the seeds.
- Place the folded towel in a mason jar, plastic bag, or Tupperware with a lid—anything airtight will do. This keeps the moisture in and maintains the right temperature.
- Set the container somewhere out of the way. For seeds like peppers that prefer warmth, place them in a window or on a heat mat. Most other seeds, especially cool crops, will do fine on the counter.
After a day or two, check on your seeds. If some have sprouted, you can remove them, add them to your compost, and record the number in your garden planner. If seeds remain, dampen the towel again and put them back in the container.
Continue checking every few days, keeping the towel moist but not too wet. Most seeds will germinate within a week, though some may take a bit longer. Be patient, and if you’re unsure how long it should take, check your seed packet.
The Jar Germination Test
Some seeds, particularly herbs, need light to sprout. If the seed packet says to “surface plant,” this means they require light. Here’s what to do for those seeds:
- Place a few dampened paper towels in a jar, ziplock bag, or clear container.
- Lay the seeds on top of the towels.
- Place the container near a light source.
The rest of the steps are the same as with the paper towel method. Just keep an eye on the moisture levels and gently spray the seeds as needed.
A Note on Testing Peppers and Tomatoes
Peppers, tomatoes, and some flower seeds need a little extra help. They require potassium nitrate to germinate, which paper towels and water alone don’t provide. You can find potassium nitrate at the garden center. Mix a half teaspoon into a quart of water, and use this solution to spray the seeds during the test.
What to Do With The Results
After you’ve finished your tests, be sure to record everything in your garden log. To calculate the germination percentage, divide the number of healthy seedlings by the total number of seeds tested, then multiply by 100.
If you have a low germination rate, you can try sprouting the seeds in seed starter mix—they might just need some soil to get going. If that works, they could be salvaged for the garden, unlike the small sprouts from the paper towels.
But if your seeds don’t sprout well using these methods, it might be time to buy new seeds. While you can plant seeds with low germination rates, don’t expect too much. If it’s something you really want to grow, make sure you have fresh, viable seeds.
Now that we’ve had some fun with this little science experiment, we know what we can and can’t depend on when it comes to our saved seeds.
If only I had an endless supply of seeds—I’d test them all, just because it’s winter and I love watching things grow. But alas, I don’t…
Spring will be here soon, my friends. Soon.
I hope you found this seed testing guide helpful as you prepare for a bountiful garden season! If you have any questions or tips to share, I'd love to hear from you in the comments. Don’t forget to follow me on Facebook and Instagram for more gardening inspiration and updates.
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