There is an easy way to tell if the seeds inside an old seed pack are still good — before going through the time and trouble of planting the seeds in the garden to find out. In this video, I’ll show you how to check seeds for viability and test their germination rate.
Seed packets typically state the planting year that the seeds were packaged for as well as the germination rate. As years go by and the seeds age, the germination rate declines, faster or slower depending on the variety of seeds and how the seeds were stored.
Seeds that you received from a friend or from a seed swap may have no date at all and were likely never tested for their germination rate. The good news is, you can test seeds yourself, and it’s not hard at all.
The Germination Test
The point of the germination test is to determine if you need to plant a few extra seeds to get as many plants as you want, or if you should not bother planting those old seeds at all.
First, take a paper towel and moisten it with a spray bottle. Place 10 of the seeds to be tested onto the paper towel, then carefully fold the wet paper towel over the seeds. Place the paper towel and seeds in a plastic bag, seal it, and label the bag with the variety and the date.
Place the plastic bag in a warm environment — like the top of the refrigerator — and after a few days, begin to check the seeds daily. Depending on the variety you are testing, the viable seeds could sprout in just a few days. Other varieties may take up to several weeks.
If nothing happens after waiting the appropriate length of time, you know the seeds are no good. A low number of sprouts will mean you need to plant more thickly, and a high number of sprouts means you can plant at the regular seed density.
Testing with exactly 10 seeds makes the math really easy: If nine out of 10 seeds sprout, the germination rate is 90 percent.
You can do the germination test at any time, but if your tested seeds have sprouted at their planting time, you can move them into your garden.
Links & Resources
Some product links in this guide are affiliate links. See full disclosure below.
Episode 37: Starting Seeds Indoors: The Non-Negotiables for Success, Pt. 1
Episode 38: How to Start Seeds Indoors: The Non-Negotiables for Success, Pt. 2
Episode 39: How to Start Seeds Indoors: Digging Deeper, Pt. 3
Episode 125: Saving Seeds: The Basics, the Benefits and Beyond
joegardener Seed Starting Charts: Seed Inventory Chart and Seed Longevity Chart
joegardener blog: The Best Soil Temperature for Seed Germination
joegardener Online Gardening Academy™: Three popular courses on gardening fundamentals!
joegardener Online Gardening Academy Master Seed Starting: Everything you need to know to start your own plants from seed — indoors and out.
Corona® Tools – Video sponsor and Brand Partner of joegardener.com
*Disclosure: Some product links in this guide are affiliate links, which means we would get a commission if you purchase. However, none of the prices of these resources have been increased to compensate us. None of the items included in this list have any bearing on any compensation being an influencing factor on their inclusion here. The selection of all items featured in this post and podcast were based solely on merit and in no way influenced by any affiliate or financial incentive, or contractual relationship. At the time of this writing, Joe Lamp’l has professional relationships with the following companies who may have products included in this post and podcast: Rain Bird, Corona Tools, Milorganite, Soil3, Exmark, and Wild Alaskan Seafood Box. These companies are either Brand Partners of joegardener.com and/or advertise on our website. However, we receive no additional compensation from the sales or promotion of their product through this guide. The inclusion of any products mentioned within this post is entirely independent and exclusive of any relationship.