Make Sure Your Seeds Are Good to Grow Next Year

When seed companies put dozens or even hundreds of seeds inside each little package, they're thinking of small-scale farmers and homesteaders, not kitchen gardeners with a couple raised beds to fill. That leaves many of us with leftover seeds at the end of each growing season.

So how you do store those seeds so that they're still viable next year?

I say "viable" instead of "good" because seeds are, after all, living things in a dormant state. We want to keep them dormant until we're ready for them to do their thing. And we also want to protect them from mold and mildew.

With that in mind, remember three rules, or conditions, when it comes to proper seed storage: keep them cool, dry, and dark. This trio is basically the opposite of what seeds need to sprout and grow: warm soil, lots of moisture, and light. Let's look at how you can meet these conditions in your home, short of building your own little seed bank in your backyard.

Store Seeds Somewhere Cool

Seeds don't really go "bad", but they do lose viability over time. Since they're living things, they can also die if they're exposed to too much heat or cold. Another bad thing would be giving seeds warmth and moisture at the same time, which might cause them to sprout prematurely. And no one wants that.

Seed banks are kept cold (like -1°F cold!). Don't worry—you don't have to turn your home into a winter wonderland for the sake of your seeds. You probably already keep your house at a cool temperature (around 70°F), so your goal is just to pick a spot that stays a pretty consistent temperature year round. Avoid places next to air vents, which will have large temperature fluctuations.

Some people put their seeds in the freezer, but I personally don't think that's a good idea for us hobby gardeners. The seeds must have a specific amount of moisture remaining inside (15% to 25%) so that they stay alive but are able to be frozen.

Good Options

The basement (if it's low humidity), closets and pantries, kitchen cabinets, office drawers, underneath the bed.

Bad Options

The garage or that old storage shed out back. The fridge and freezer are risky options.

Keep Seeds Dry

Not only can moisture cause mold and mildew, it can also fool your seeds into thinking it's time to wake up and sprout.

In seed banks, the seeds are dried to the optimal moisture content, sealed into moisture-proof bags, put into a box, and then kept in their humidity-controlled seed vault. We don't have to do all that in our homes because we just need these seeds to stay viable another year or two, not another century.

The best way to keep your seeds dry is to store them in an airtight container.

Good Options

A mason jar, a ziplock baggie, a freezer bag, a recipe card box, a metal toolbox, a repurposed spice shaker, or a plastic container with a tight-fitting lid. You can keep seeds inside their original packet or in a seed envelope; then just place those inside your seed storage container of choice. If you're using a plastic bag or something not fully airtight, throw in some rice grains or one of those little desiccant packs that come in shoe boxes and new purses to absorb excess humidity.

Bad Options

An open container in your laundry room or bathroom, the most humid rooms in your home.

Pick a Dark Spot for the Optimal Storage of Seeds

I like to think of light as a speeder-upper of things: fading, sprouting, growing, drying, etc. When it comes to seeds, light can speed up germination or just loss of viability.

Most of the spots in your home I've already suggested (pantry, cabinet, desk drawers) likely don't receive direct sunlight. If your seeds are somewhere lights are being turned on and off, put them in a storage container that will block this light.

You also want to make sure to bring your seeds inside out of direct sunlight as soon as possible after you've been planting in the garden.

One More Consideration for Seed Storage

If you could potentially have pests in your home that would consider your seeds a tasty treat (things like mice, rats, weevils, and moths), make sure to use a seed storage container that they can't eat their way through. Mason jars and metal containers are good options.

Seeds Will Still Lose Viability Over Time, Even When Stored Properly

Here's the thing: No matter how cool, dry, and dark you keep your seeds, they will lose viability with each year. (I mean, unless you desiccate your seeds, seal them inside a moisture-proof foil bag, and keep them in a humidity-controlled vault surrounded by permafrost. I personally don't have the time or permafrost for that.)

Seeds just naturally degrade over time. By degrade, I mean the likelihood they'll ever germinate and grow decreases. Seeds were meant to sit in the soil for a couple seasons and then sprout. They're not meant to be kept in little paper envelopes on your pantry shelf for years and years. Some seeds, unfortunately, will lose viability faster than others. You might grow a healthy pumpkin plant from a five-year-old seed, but that parsnip seed only has about a 50 percent chance of sprouting after one year. (Learn more about how long different types of seeds typically last.)

Overall, you'll have the best success rates when you plant your seeds as close to their packaging date or collection date as possible.

How to Organize Seeds Within Your Storage Container

I recommend sorting seed packets based on their preferred growing season: cool, warm, and hot. That way, when you're, say, approaching your last frost date, you know which plants can be planted soon and which ones will need to wait until all threat of frost has passed. If you always plant at specific times, you could also arrange seeds by months.

Within each seasonal or monthly category, you could group plants by the categories of leaves, roots, and fruit. Put all your herb and leafy green seeds together, all your root crops together, and all your fruiting plants together. Or you could group plants by size. You might put root crops like carrots and radishes in with small leafy greens, and broccoli and cauliflower in with other large plants like kale and Swiss chard.

This would make it really easy to look through what you already have when you're planning out your garden for the next growing season.

How to Check Whether Seeds Are Still Good After Being Stored

The first thing you want to do is check for mold, rot, or damage caused by insects. You can certainly check the "use by" date on the seed package, but know that these aren't the same as expiration dates. You don't have to throw out all your seeds if you're past that date. It is a good idea, though, to do a quick germination test to get a sense of how many of your seeds are likely to sprout in your garden.

Steps to Conduct a Germination Test

• Spread out 10 of the same type of seed on a damp paper towel.
• Roll up the paper towel and place it inside a plastic bag.
• Place the bag in a warm spot.
• Keep the paper towel damp but not soaking wet. Spray it with water as needed.
• Once 7 to 10 days have passed, check to see how many of the seeds have sprouted.

Multiply the number of seeds that have sprouted by 10. That's your germination rate (2 seeds equal 20 percent, 5 seeds equal 50 percent, etc.). If your rate is less than 70 percent, you can still plant those seeds in your garden if you want—just sow them more heavily than you normally would to up the chances that some of those seeds becoming seedlings. If your germination rate is less than 50 percent (or if the seedlings that emerged seemed stunted), consider starting over with fresh seeds.

You can carefully transplant seeds that sprouted during the germination test to your garden if the growing conditions are ideal for them.

Tips to Prevent Having a Ton of Seeds to Store Every Year

Like I said, seeds aren't packaged with gardeners who want to grow a few of our favorite plants in mind. Most of us don't even need half of the seeds inside those packages any given season. So here are four tips to reduce the overall number of seeds you have to buy and/or store at the end of the season:

• Split your seed orders for large plants like tomatoes, peppers, and squash with a couple of gardening buddies. You'll each pay less and probably still end up with more seeds than you really need. At least you won't have 70 percent of seeds in a package go to waste.
• If you have a bunch of seeds for small plants like lettuce or arugula, just broadcast them in a garden bed. No need to plant sparingly. Harvest some leaves every single day to keep the plants small, and you'll have daily homegrown salads.
• Make your planting plan before you shop for seeds or open a seed catalog. This one's more about self-control when confronted with all the cool heirloom options out there. Knowing what you actually intend to grow will prevent you from over-ordering and wasting seeds.
• If you have a whole bunch of seeds for plants with edible leaves and stems (think radishes, kale, basil, etc.), toss them in a tray filled with organic seed starting mix and put them under a grow light. In just 10 to 21 days, you'll have your own microgreens.

I'm really one to talk here because I have tubs and tubs full of unused seeds. Do as I say, not as I do, right?

One more thing: the quality of seeds you buy also impacts how long you can store those seeds. Avoid those colorful displays at big box stores and prioritize buying organic seeds from local sources or reputable seed companies online. Some of my favorites are Baker Creek, Botanical Interests, Johnny's Selected Seeds, High Mowing Seeds, and Southern Exposure Seed Exchange. 

Keep Cool, Dry, & Dark in Mind for the Best Seed Storage at Home

Remember that each seed you're taking the time to store properly is a living thing that's capable of becoming delicious and nutritious food for you and your family. Seeds are basically little pieces of magic wrapped in seed coats. So store 'em properly and look forward to the miracle of life that is germination next season and hopefully the season after that!

Thanks for helping me make gardening ordinary once more!