There are always more seeds in a packet than a backyard gardener can use in one year. It’s nice to have a stash for next season, …unless you pull out the old packets and get a disappointing germination rate. Then you have to hope the garden center hasn’t yet packed away the seed display to make room for the 4th of July decorations… in May.
Seeds last don’t last forever. Those that remain viable for 4 or 5 years, like kale and Swiss chard, are the exception, not the rule. Even when stored in the best of conditions, you are still going to have to anticipate a less than 100% germination rate.
Which brings me to… how do you store seeds so they stay fresh? Smart of you to ask that question in the fall, not when you go to grab your seeds for planting in the spring.
The two main things to keep in mind are cool temperatures and dry conditions. Seeds are very much alive and they can be destroyed quickly if they get too damp or too hot. Luckily most of us have a few cool spots in our homes during winter, so that should not be a problem. Basements and dark closets are perfect for this.
How Cool is Cool?
You don’t need to sacrifice fridge space, to save seed. You could store them in the fridge, if you wanted to, as long as they are in an airtight container so that no moisture gets in. But for most of us, a spot that doesn’t get much above 70 degrees F. is perfect and that’s just about everywhere in the house that isn’t being directly heated.
You want cool temperatures, but you also want steady conditions. An unheated garage is not usually a good choice for storing seeds. The temperature will fluctuate all over the place and moisture is often an issue. Be kind to your seed and bring it indoors for the winter.
There are a handful of exceptions to the cool temperature rule. (Aren’t there always?). Onions and leeks are notoriously fussy about being stored. Their viability decreases rapidly. Seeds in the carrot and parsnip family are not far behind. Generally you will want to buy fresh seed every year. However if you want to try saving some – either left over or just harvested – you’ll have better luck keeping them in the freezer. The seeds are very small, so they won’t take up too much real estate.
How Do You Know if Your Seeds are Dry Enough to Store?
Before you even consider tucking your seed away, it needs to be dry enough to snap. This shouldn’t be a problem with left over seed, but if you are storing seed you’ve saved yourself (good for you), you will want to be absolutely certain they aren’t holding on to moisture.
If the seed is pliable or has any give when you try to bend it, hold off. Spread the seed on a screen or somewhere where it will get very good air circulation and be patient. Test it every few weeks and when it is dry enough to snap or resist your attempts to bend it, it is ready to be stored.
How to Keep Seed Dry in Storage
Remember, seeds are still very much alive. They are just waiting for a little warmth and moisture, to germinate and start growing. Now that you’ve been patient and allowed your seed to become dry to the point of being brittle, you don’t want to waste that effort by storing them in damp conditions.
It’s really pretty easy to keep your seed dry. Store your thoroughly dried seed in envelopes and then place the envelopes into an airtight container. The envelope serves two purposes. First, if a slight amount of moisture should remain or sneak in, it will wick it away from the seed. And secondly, you can write the type of seed and the year on the outside. Don’t think you’ll remember. You won’t.
The most popular airtight container is a canning jar. If you have a great deal of seed, you are going to need a big jar or multiple jars. Zipper plastic bags are iffy for this job. You can’t be guaranteed they will keep all moisture out.
Alternatively, some seed savers think it’s better to give your seeds some air and breathing room. Seeds do need some oxygen around them, but the inside of an envelope usually provides enough for the time they are in storage. However there is a school of thought that believes storing them in open or permeable containers is a better route to take, because it allows any moisture from respiration to escape. I’ve never gone this route and I think if you ensure your seeds are brittle-dry before storage, you are better off with airtight containers. There are other dangers lurking, that could get into open containers.
Even as Seed, Plants are Beloved by Pests
As if fending off garden pests during the growing season were not enough, pests like mice and insects will consider your stored seed a winter treat. Even a curious pet can create quite a mess, if allowed to get into the seed, …the little dears.
How Long Do Vegetable Seeds Last?
Here’s a chart of most commonly grown vegetables and how long you can generally expect them to remain viable. I said generally, because you never know.
|1 Year||Onion, Parsley, Parsnip, Salsify, Scorzonera|
|2 Years||Corn, Leeks, Okra, Peppers, Spinach|
|3 Years||Beans, Broccoli, Carrots, Celeriac, Celery, Kohlrabi, Napa Cabbage, Peas|
|4 Years||Arugula, Beets, Brussels Sprouts, Cabbage, Cauliflower, Chicory, Eggplant, Fennel, Kale, Mustard, Pumpkin, Radish, Rutabaga, Sorrel, Squash, Swiss Chard, Tomato, Turnip, Watermelon|
|5 Years||Collards, Corn Salad (Mache), Cucumber, Endive, Lettuce, Muskmelon, Watercress|
Testing Your Seeds, before You Plant Them
If you want to be certain your saved seeds will sprout, you can always test a few before you plant them in the garden. The process is simple and quick.
What You Will Need
- 10 seeds
- Paper towels
- Plastic bag
- Waterproof pen or market
1. Dampen a paper towel. You want it to be moist throughout, but not dripping wet.
2. Count out 10 seeds and strew them in a row on the dampened towel.
3. Roll up the paper towel around the seeds.
4. Take the rolled towel and place it into a plastic bag. Write the date and the type of seed on the bag and then seal it.
5. Keep the plastic bag in a spot that is about 70 degrees F.
6. Check it daily for signs of germination. If the towel is starting to dry out, spray it with water.
7. Unless your seed takes a longer than usual time to germinate, such as parsley, you should see germination within 7 – 10 days.
8. So on day 10, open the paper towel and count how many seeds have germinated, to get the percentage germination day. This is easy to figure, since we used 10 seeds. If all 10 sprouted, you have a 100% germination rate. If only 6 sprouted, it’s a 60% rate. Three sprouted would be a 30% germination rate…
If you get a germination rate of 70% or more, fantastic. Use the seed, but you might want to sow a little more heavily than you would with new seed.
If your germination rate is below 70%, you’d be better off buying new seed. Who needs to go through all the effort of planting and tending to get only a handful of plants?
You can go ahead and plant the test seeds that have germinated. No sense in wasting them. Be very gentle with them. It’s easy to break the tiny root or growing tip. If they are growing through the paper towel, don’t try to pull them lose, just sow them with the towel attached. It will disintegrate quickly.