When I first started gardening, I would get sucked in at the seed section when I went to the store. The pictures on the seed packets looked so enticing. How could I choose just a couple of packets? Inevitably, I would buy too many seeds. Find out what seeds I recommend beginner gardeners start with.
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The seed packets all have a “packaged date.” I thought it was like the expiration date on a yogurt carton (though I've pushed the envelope on those dates a few times). I thought I had wasted all of the seeds that I didn’t use within the current season and I had to throw them away.
Wrong! I heard something about saving seeds for years. That was good news to me. But how long can you really save seeds? I’ve found many tables and charts online that specify different seeds and how many years you can continue to use them.
But how do you really know that it’s time to throw those old seed packets away?
I know many of you are probably a lot like me in that you do not like to waste anything or throw anything away if you don’t have to (hence why we eat yogurt that may or may not be a little past it's expiration date). Who, other than a gardener, goes out of their way to gather trash to make compost and then proceeds to call that compost "black gold"? I just can’t bring myself to throw away any seed. Instead of guessing, a helpful way that I have found to check to make sure seeds are still viable for planting is to test the germination rates.
Benefits of Testing Germination Rates (Seed Viability):
This is such a simple process. I think you’re going to wonder why you didn’t do this a long time ago. By checking your germination rates (seed viability) ahead of planting, you will gain these benefits:
Now, before you check your germination rates, it’s important for us to talk about how you store your seeds. You may have very different outcomes based on whether you store your seeds in a cool refrigerator or whether you store your seeds in a hot garage.
Two main things you should think about when storing seeds are humidity and temperature. Seeds will last longer if they are stored in a place with low humidity and low temperature (think 32 to 50 degrees Fahrenheit). A refrigerator is an ideal space to store seeds.
Another thing to keep in mind when checking for viability, or how many seeds germinate, is that this test does not check for seed vigor. Seed vigor is how healthy the germinated seeds are. Will they be able to make it through their life cycle, or will they sprout and then stop growing?
Unfortunately for us, there’s not really a good test of seed vigor for home gardeners. One way to avoid this issue is to buy new seed every year. If you only have one chance to get the seeds going, and you are worried about their vigor, it may be worth it to start fresh. I like to live on the wild side. I try to store the seeds in the best conditions possible and hope for the best when it comes to vigor. I would rather take the risk based on the germination rate and see what happens.
How long should you keep seeds? Are they just too old?
Some seeds are supposed to keep better than others. There are no hard and fast rules for how long seeds will last. A lot of their viability depends on how they were stored (moisture and temperature).
I looked at a few different resources across the internet to see how long various seeds should be kept, and the recommendations vary. Here are some of the vegetables I looked up with the range of years that they may stay good:
As you can see, something like lettuce can last from one to six years. That’s a pretty big spread. Some time frames I found were more consistent, such as okra lasting for two years. I would still check the viability of my okra even if it’s three or four years old. If you have stored your seed properly, it’s worth it to see if you can use what you already have on hand.
How to Test Germination Rates (Seed Viability):
First, pick out the seeds you want to test. You want to test at least ten seeds to get a good idea of the germination rate. If you don’t have enough seeds or you don’t want to use them up on a test, just skip that variety. You can always plant them and see how they do. Once you have chosen the seeds you want to test, grab the rest of your supplies. You will need:
1. Wet your paper towels and wring them out so they are damp, not dripping.
2. Lay the paper towel flat on a table.
3. Lay ten seeds in a row at one end of the damp paper towel.
4. Roll up the paper towel.
5. Write the type of seed and the date on the plastic baggie.
6. Place the rolled paper towel in the baggie.
7. Close the baggie, but don’t try to get all the air out. You want the seeds to have air so they can germinate.
8. Place the baggie of test seeds in a warm place. On top of the refrigerator is ideal. You want it to be at least 70 degrees Fahrenheit.
9. Check every day or two to make sure the paper towel is still wet. If it has dried out, spritz it with some water.
10. Depending on the seeds, it can take anywhere from two days to fourteen days to germinate. A good rule of thumb is to let them sit for seven to ten days. By that point, most of the seeds should be germinating.
11. After you have let the seeds germinate, check to see what the germination rate is for each type of seed. If you used ten seeds, it will be easy to figure out your germination rate. Simply count how many seeds germinated, and that’s your rate!
Example: 10 seeds tested. Five seeds germinated. That means you have a 50% germination rate.
Example: 10 seeds tested. Eight seeds germinated. That means you have an 80% germination rate.
The higher the germination rate, the better. If it’s under 60%, you may decide to buy new seeds. If you still want to use seeds that had a low germination rate, just over seed them. Remember, this doesn’t test the seed’s vigor.
If your germination rate was over 60%, you will be more likely to have a good germination rate in the garden. If you have a 70% to 90% germination rate, you are good to go. If your germination rate is 100%, keep doing what you are doing!
If you use more or less than ten seeds for your test, just divide the number of germinated seeds by the total number of seeds tested to find your germination rate.
Once you have finished your testing, you can plant any germinated seeds outside if it’s warm enough. You can also feed the sprouted seeds to your chickens or throw them in the compost.
I just tested a handful of seeds that I have on hand. A few of them were older. I also had a couple that I just tried planting without much luck. I wasn’t sure if it was the seeds or the growing conditions (it’s the seeds).
I tested some cucumber seeds from two years ago. I did eight seeds, because there weren’t too many left in the packet. All eight of them germinated within five days! 100%! Woohoo! Then I had some lettuce seeds from last season. After five days, they are all duds! Guess what? I stored them all the same way – not necessarily the best conditions (I know, I know! I’m getting better at following my own advice). But what gives? Maybe the lettuce seeds weren’t as strong to begin with. Maybe I did something. It’s hard to say.
But I’m not going to worry about it. I will probably dump them all out in the garden in a small area to see if any of them germinate, just in case. I guess this is another lesson learned from gardening. You can treat two seeds in the exact same way but get a different outcome.
Another one that was surprising was the onion seeds I tested. Most sources say they are only good for one season (some sources say up to three). I had a 60% germination rate on my season-old onions after seven days. Now, that’s not 100% like the cucumbers. But you can bet I am planting those little guys. Again, I will seed them a little on the heavy side, just to be safe.
There’s the other gardening lesson. Just because sources say you can only use those seeds for one year doesn’t mean that’s the case every time. It’s best to do your own test. Use your best judgement.
Now that you know how to test your seeds for viability, you can save yourself some time and heartache waiting for unviable seeds to come up. What will you do with all the extra time you have now? Probably plant more seeds!