How Tell If Old Garden Seeds Will Germinate
If you have old seeds sitting around and are wondering if they will grow, there is an easy test you can do to find out!
We’ve all done it. We ordered too many seeds for our garden, grabbed some discount seeds at the end of last year, or maybe we were gifted some seeds from a friend.
We tucked them away in our seed stash and before you know it, you are suddenly finding seed packets that are five-plus years old.
Do Garden Seeds Expire?
Yes and no. Sorry it isn’t a simple answer!
Fresh seeds that are from the last year or two are most likely going to give you the best germination rate and yield healthy plants.
Garden seeds typically will still work fine for a few years after their test date. The viability of smaller seeds goes down quicker, and large seeds will maintain viability longer.
There is a really cool story about seeds found in a cave in Kentucky that were believed to be thousands of years old. The atmosphere of the caves kept them well preserved.
They were planted, and they grew! The resulting squash wasn’t very tasty and pretty small, but it’s still amazing that the seeds were able to grow after all those years.
The bottom line is, seeds will usually work for several years past the point of their germination test date, but the amount of seeds that will actually grow will reduce year after year until it isn’t worth planting them anymore.
Why Do Seeds ‘Go Bad’?
Often times this has to do with the protective outer layer called the seed coat. As this coat ages and wears, the inner part of the seed, which contains all the parts that will sprout and grow, becomes exposed. If it is damaged physically or by mold/bacteria/etc. then it will stop being viable.
Things also just grow old with time and will be less effective if planted out.
How Can I Tell If My Garden Seed is Old?
Seed companies put a “test date” on the seed packet along with the germination rate. Here is an example from the sugar snap peas used in the YouTube video demonstration
You can see that these peas were tested for their viability in November of 2019.
They might not have been grown that season. They could have been grown a year or two earlier, but the seed companies are required to test them annually before sale to make sure they germinate at LEAST the minimum required rate by law.
Most seed companies will only sell seeds with 90% germination rate and above.
Supplies for Testing Seed Viability
What I love about this method is how simple it is. I can almost guarantee you have the supplies in your house right now!
- Plastic Ziplock Bag (even an old plastic bag would work honestly)
- Piece of Damp Paper Towel
- Warm Place (Top of fridge is what I recommend)
- Old Seeds
How to Test if Garden Seeds are Still Good
Begin by moistening the paper towel. It should be wet enough that when you squeeze it a little smooshy sound happens, but not so much it is dripping off your hand.
Lay out the towel. Place your seeds for testing along one edge of the towel. How many seeds you decide to test is up to you. I like to use ten seeds as a good starting point, but of course your accuracy will go up the more you test.
Roll them up snuggly in the wet towel but not super tight.
Place the towel with the seeds inside a plastic Ziplock bag. Seal it up.
Put the bag on top of your fridge. Your fridge is a nice consistent heat source that isn’t too hot and is the perfect temperature to help along the germination process!
Note the date on the calendar or write it on the bag.
Check the seeds after the minimum amount of germination days have happened. If they haven’t sprouted yet, give them more time. Once you reach the last suggested germination day, it is time to look at your results.
Looking at the Results
When testing ten seeds, it is very easy to get the percentage/rate. If 8/10 seeds sprouted, you have a 80% germination rate. If 5/10 sprouted, it is 50%. So on and so forth.
If you got a great germination rate of 90% or above, you can go ahead and plant the seeds as recommended on the packet.
If you had a lower germination rate, say 60-70% or lower, then you might want to consider planting them differently or getting new seeds.
With a lower germination rate for example, you might choose to plant two seeds per spot instead of just one. This increases the chance you won’t have gaps in your garden.
What is the Ideal Germination Temperature?
This can also vary from seed to seed. Most seeds will do well and germinate around 70F. Though cooler season varieties might do well at slightly cooler temperatures.
In my experience the top of the fridge has worked well for doing this sprout test with tomatoes, kale, peas, and carrots!
How Long Does It Take Seeds to Germinate?
This will depend on the type of seed you are trying to grow. Tiny seeds tend to take longer to germinate and larger seeds germinate more quickly.
Each plant usually has a range. The pea seeds for example said they could take anywhere from 6-14 days.
Here are some common garden seed varieties and their germination times. This information is often on seed packages but not always.
- Tomato, 5-10 days
- Cucumber, 3-10 days
- Pepper, 7-21 days
- Zucchini, 4-10 days
- Eggplant, 7-14 days
- Carrot, 14-21 days
- Beets, 5-12 days
- Spinach, 7-14 days
What is the Best Way to Store Seeds?
Whether you have flower seeds or vegetable seeds, it is a good idea to keep them in ideal storage conditions so they will continue growing well for years to come.
Seeds should be stored in a dry place that is relatively cool. An airtight container can also be helpful for seed storage. It is best to keep them in a dark place or at least out of direct sunlight, as UV exposure can weaken their seed coat we talked about earlier.
At the end of the year, go through what seeds you have left and write them down. You can also make note of their last germination test date.
Make sure you use or test older seeds in the garden the following year. I like to mark the top of the seed packet with a highlighter so it is easy to remember “oh yeah, I need to plant those this year!”
What to Do With Bad Seeds?
Any out-of-date seeds that didn’t germinate can be tossed in the compost, fed to chickens, or just scattered to the wind.
Looking for more from the garden?
I have been a Master Gardener in Minnesota for over a decade! I have tons of great gardening articles you might like to check out below.
