I have never been much of a seed collector, preferring to buy seeds, get transplants, or make cuttings. My experience with saving, trading, and using seeds has been hit or miss, probably partly because I didn’t know how old they were. Here’s what I’ve learned.
How Long Before Seeds Go Bad?
Seeds can retain viability for years if stored correctly. The Global Seed Vault in Norway stores seeds from a variety of plants to help ensure food supply and for research. The project expects it can keep seeds viable in deep, cold storage for hundreds, if not thousands, of years.
The secret then to knowing how long you can keep a seed and still grow a plant is how it has been stored. Under the right conditions, namely dry and cold, seeds can still germinate many years later.
How to Make Seeds Last Longer
If you collect or trade seeds, or even if you buy packets but don’t use them all at once, the right storage will help you keep them longer.
First, make sure seeds are 100 percent dry. Any moisture can lead to viability loss. With this in mind, you also need an airtight container. This will keep out any moisture from the air during storage.
Here’s a useful tip for keeping your storage area dry: save the silica packs from pill bottles and new clothing and put them in your seed containers. They absorb water from the air.
Finally, the seeds need to be cold to last a long time, hence the vault being in Norway. A freezer is best, but you can also store seeds in the fridge.
Are My Seeds Still Good?
As someone who is a little unorganized, I have wondered this many times only to plant the seeds without knowing and get little or no growth. Over the years I learned how to test an old, undated seed packet without just planting them all and hoping for the best.
Put test seeds on a wet paper towel inside a sealable plastic bag. Leave it in a warm spot for a few days to a couple of weeks to get an idea for how many will germinate. For instance, if you test ten seeds and only four germinate, you can expect that about 40% of the seeds are viable. You would need to plant 25 seeds to get ten to grow.
Getting Old Seeds to Germinate
If you have older seeds, or those of questionable age, a little extra effort may lead to a higher germination rate:
- Soak older seeds in a 1 or 2% hydrogen peroxide solution to clean off any mold or other microorganisms.
- Hydrogen peroxide can also provide chemical scarification, a way of softening the hard outer sell of the seed to promote germination.
- You can scarify an old seed a little more aggressively with mechanical methods. Use sandpaper to rough up the edges or cut a small nick in the seed with a knife.
- Use high-quality, organic soil to start any seeds but especially for older ones. Keep them warm and maintain moisture in the soil for the best results.