If you like to start plants from seed, you know that you hardly ever use up all of the seeds in every seed packet. It’s nice to build up a stash of seeds, and to be able to use those seeds for a few years after you buy them. One of the most comment questions I get from new gardeners is How Long Do Seeds Last? Many seeds can be stored for several years, but the viability of seeds will go down over time. It’s a good idea to test the viability of old seeds before you sow them to make sure it’s worth your time and effort, by performing a simple seed viability test.
Related Post: Storing Seeds
Seed Viability Test
- Zipper baggie
- Paper towel
- Old seeds
- Marker or pen
You can use as many seeds as you want for the seed viability test, but I recommend using ten seeds for easy math. If you don’t have that many seeds to spare, then you can use fewer seeds, but I wouldn’t use less than five seeds otherwise your seed viability test won’t be very accurate.
How To Test Viability Of Old Seeds
- Wet down the paper towel, wring it out and lay it on a flat surface
- Place seeds on paper towel so they aren’t touching each other
- Carefully fold the seeds into the paper towel
- Write the name of the seed on the baggie (and the date if you’re starting seeds on different days)
- Place the moist paper towel into the baggie and seal it up
- Put it in a warm location (out of direct sunlight)
- Check the seeds every couple of days to see if any have sprouted. You can usually tell by looking through the baggie, but sometimes you have to remove the paper towel and unfold it to check the seeds.
Some seeds take longer to sprout than others. In my seed viability test, it only took a couple of days for the bean seeds to start sprouting. Pepper seeds are much slower to germinate, and I didn’t see signs of germination until the 6th day of my seed viability test. Most seeds will start to sprout within a week, but let them sit in the baggie for two weeks before you give up.
Seed Viability Test Results
(use this chart if you used 10 seeds for your seed viability test, adjust the math if you used a different amount of seeds)
10 seeds sprouted = 100% viability
8 seeds sprouted = 80% viability
5 seeds sprouted = 50% viability
1 seed sprouted = 10% viability
You get the picture. So, depending on the germination rate of your seeds, you can plan to start more seeds to compensate for the low viability of old seeds. Plan to start more of the seeds with a lower germination rate. For example, if your seed germination rate is only 50%, then plant twice as many seeds than you need. If the seed germination rates are in the 80-100% range, then you know to start less seeds.
Related Post: Tips For Starting Seeds Indoors
After the seeds you used for the seed viability test have sprouted, you can plant them if you want, just be careful not to break off any of the delicate roots.
More Tips For Growing Seeds
- Seed Starting Equipment & Supplies
- Disinfecting Seed Flats and Trays
- DIY Seed Starting Mix
- How to Germinate Castor Bean Seeds
- Tips For Starting Seeds Indoors
For more information about how to start seeds inside, and tons of tips for starting seeds indoors, click here… Sowing Seeds
Have you done seed viability testing for your old seeds? Leave a comment below and share your experience.