I learned years ago how to test seeds for viability when I was gifted a bunch of outdated seed packets and was curious about their germination rate. Testing seeds to see if they are viable is a simple, easy process and makes a fun homeschool science project for the kids!
We test seed viability and germination rate anytime I come across a pack of outdated seeds in my stash or an envelope of seeds we saved and forgot to write down the harvest date.
We have been saving heirloom seeds for a number of years. When I really started getting serious about it, I bought a box of these little paper envelopes to store them in. That way the seed envelopes were all the same size and made organizing a lot easier.
If you didn’t already know that I love to keep my seeds organized and tidy read this and find out my easy method for seed organizing!
When we put seeds in one of the seed envelopes, we always make sure we write on it what the plant is, where it was grown and the year harvested.
Two years ago we saved several paper bags full of heirloom seeds from our garden that needed to be threshed. We had seed bags of radish, spinach, peas, sunflowers and chard.
The big bags of chard seed were abundant and set aside in one of our sheds to continue drying. The other seed bags were set aside in our home office out of direct sunlight to let the seeds continue curing before we threshed them.
Unfortunately last year I was dealing with some health issues and didn’t get a chance to do anything with these bags of saved seeds. I came across them the other day and felt really sad at the thought that all our hard work nurturing these plants and saving these seeds may be for nothing.
I decided to test their seed viability and had very low expectations. I thought for sure that we wouldn’t have more than a fifty percent viability rate if even that. Read on to find out the results!
Why test for seed viability and germination?
If you go to all the effort to plant seeds in your garden, it is devastating to discover that your seeds were not viable and had a low germination rate.
I’ve had this happen before and it is a heartbreaking experience.
When it happened, I bought new seed and reseeded that garden bed, but by that point I was behind in the growing season and the conditions were not ideal for that plant.
Ever since then I make sure I check seed packets for dates and test for viability and germination rate when needed.
Setting up the Seed Viability Test
You may have heard about the method of testing seeds for validity that involve seeing if they will sink or float in water.
I’ve read that this isn’t a very reliable method so we choose to do the damp paper towel method. I’d rather be safe than sorry when testing our seeds’ germination rate!
The materials you need to test seeds for viability:
-paper towels (we used one piece of the select-a-size for each seed variety)
-sealable plastic bag
The seed viability test is a great project for kids to participate in. We did this as a homeschool science project and it was a great real life example of validity rates for Big Sister!
Testing the seeds for germination:
1. Wet the paper towel so it is damp.
2. Lay the paper towel out on a flat surface. Place one variety of seeds on the paper towel starting about half an inch from the edge. Space the seeds with about half an inch between them. I always try to use ten seeds of each variety to make it easier to figure out the viability rate (we’ll get to that step in #6!)
3. Once all the seeds are placed, carefully roll the paper towel up enclosing the seeds inside the damp paper towel roll. You can label the paper towel if you need to. We didn’t because the seeds we were testing this year were all distinctly different shapes and we knew what we were testing.
4. Carefully place the paper towel rolls of seeds inside the plastic bag and seal it closed. Sit it in a warm spot and wait.
5. After two days, open the bag and carefully unroll the paper towel to see if the seeds started to sprout. Seeds have varying amounts of time they need to germinate so one variety may start to sprout while another variety needs a few more days. On average, seeds germinate between 2-14 days depending on the variety. Seed packets usually state germination rate on the back of the package.
6. Once the seeds have started to sprout, lay the paper towel out so you can observe the sprouted seeds. I take notes on each seed variety to record how many seeds we tested and how many sprouted. To determine your seed viability rate, figure out the percentage of seeds that sprouted out of the total of 10. For example, if only six seeds sprouted out of 10 then you have a 60% viability rate.
Step number six is where Big Sister’s homeschool math project came into play! Are you curious what we found with our seed viability test?
The Results of our Seed Viability Test and Germination Rates
We discovered that only 8 out of 10 pea seeds sprouted so we had an 80% viability rate. Our hardy heirloom chard had a 90% viability rate which totally surprised me considering they’ve been sitting in bags in a shed for two years!
Our black oil sunflower seeds, heirloom spinach and radish seeds all had a 100% viability rate.
That’s so remarkable considering they are two years old and weren’t stored in a cool, dark spot!
Now that we know the viability rates of our heirloom saved seeds, our next winter project will be finally getting them threshed, placed in envelopes and properly stored for spring planting!
What to Do With Sprouted Seeds From a Seed Validity and Germination Test
As for the sprouted seeds, what should you do with them? I ate one of the peas since to me they seem just like homegrown sprouts we make each winter but my kids weren’t too keen on that idea!
I suggested we feed them to the chickens for a tasty winter treat but Little Brother, the plant lover, was devastated by that idea.
He wanted to plant them, but unfortunately it’s below zero outside so we’re not planting them in our garden beds and I’m definitely not going out to the garden shed to find a pot of frozen soil!
Instead we decided to experiment with an aquaponics inspired idea. We carefully placed the paper towels covered in sprouting seeds inside a shallow glass dish.
We spritzed more water on them and covered the glass dish with plastic wrap to see if they will continue to grow.
One of the things I love about homeschooling is doing real-life projects like this. I especially love how one project leads to an idea for another and the learning continues!