Can Seeds Expire or Go Bad?

Wondering How Long Seeds Last?

Seeds are pretty incredible little things.

Actually, I should say, incredible living things, because seeds are, in fact, alive. Assuming that a seed has been kept under suitable conditions, it will be dormant, waiting for the right combination of water, warmth, and light to wake it up and make it burst open with new growth. This potential for growth, unfortunately, does have a window.

Humans have yet to find eternal life on this planet, and the same goes for seeds, no matter how incredible they may be. Nothing gold can stay, you know?

Can Seeds Go Bad Though?

In an ideal world, seeds would be planted as close to their packaging date as possible. Seeds can remain viable from one to six years after they're packaged, but you'll find the best success rate when you plant fresher seeds.

Think about what happens with seeds out in nature. Seeds drop from their mother plant, settle into the soil, and wait for conditions to be right for them to sprout, which typically occurs within the next 12-month-period. Seeds just aren't meant to sit in a little envelope on your shelf year after year.

Seeds will only go "bad"—in the way that bread gets moldy or milk curdles—if those seeds are exposed to moisture while being improperly stored and begin to develop mold or rot. Once they pass their "expiration date", seeds can certainly begin to degrade in quality and lose vigor, meaning the likelihood they'll ever germinate decreases. Quality does matter because we don't just want our seeds to sprout; we also, of course, want them to grow into healthy plants.

Seeds can also die if they're not properly stored, especially if they're exposed to too much heat or cold. Even if they don't die, they'll lose viability every time they experience a less-than-ideal condition.

How Long Vegetable Seeds Can Typically Last

Seed quality and seed type both make a difference in determining how long seeds can last. Let's look at the average duration of different types of seeds you might want to plant in your kitchen garden (more on seed quality in a bit).

Carrot Family Seeds

Most seeds for plants in the carrot family don't last very long. That includes seeds for carrots, celery, celeriac, parsnip, fennel, cilantro, parsley, and dill. Parsnip seeds can decrease in germination rates by 50 percent each year, no matter how well you store them.

Onion Family Seeds

Seeds for shallots, leeks, chives, and onions typically don't last much longer than a year. (I prefer to plant onions by onion sets anyways, which can last as long, if not longer, than the seeds.) Garlic bulbs for planting can similarly last about one year.

Cucumber Family Seeds

If you've held a squash or pumpkin seed, then you know these seeds feel much more substantial than something like lettuce seeds. They tend to last longer than most seeds too. Seeds for cucumbers, pumpkins, squash, gourds, and melons, including watermelons, can last up to 5 or 6 years.

Brassica Family Seeds

Seeds for arugula, broccoli, Brussels sprouts, cabbage, cauliflower, turnips, radishes, and kale can last up to 5 years, while mustard and bok choy seeds can go for about 4 years.

Amaranth Family Seeds

Seeds from this family look like they were built for self-defense, at least in my opinion. It should come as no surprise then that these seeds can hold their own for a bit. Beets, spinach, and Swiss chard seeds are typically viable for up to 5 years.

Solanaceae Family Seeds

Seeds for eggplants, peppers, and tomatoes can last for up to 5 years. Tomatillo seeds can be stored for up to 3 years. Potatoes, of course, are also in this family, but I prefer to grow potatoes from seed pieces (part of a tuber with an "eye") instead of seed. Seed potatoes should be stored no longer than 200 days.

Aster Family Seeds

Most lettuce seeds remain viable for up to 5 years in storage. (At least, this is what my research tells me. I've never had a lettuce package last more than a month in my house before I tore it open and scattered every single seed for my daily salads.)

Fabaceae Family Seeds

Beans and peas seeds can hold up for about 4 years. Perhaps thanks to their extra-thick seed coat, pea seeds often retain excellent rates of germination well into their third year.

Mint Family Seeds

Herbs have thin seed coats that typically decrease in germination rates pretty quickly. You might find that seeds fail to sprout after just one year. While that might sound disheartening, remember that many herbs are easy to grow from cuttings of mature plants.

Other Seeds

Okra seeds are typically viable for 1 to 2 years. Seeds for annual flowers are good for about 1 to 3 years, while perennial flower seeds usually make it 2 to 4 years.

How to Test the Rate of Germination in Seeds

Before you plant seeds that you've been storing for more than a year, you might want to perform a simple germination test to learn the odds of these seeds sprouting in your garden. (Or you can just do what my kids do: Scatter a bunch of seeds in the garden and hope for the best!)

Here are the steps to test germination rates:

• Spread out 10 of the seeds on a damp paper towel.
• Roll up the paper towel and place it inside a plastic bag.
• Place the bag in a warm spot.
• Feel the paper towel every couple of days and spray it with a water bottle as needed.
• After 7 to 10 days, check to see how many of the seeds have sprouted.

Multiply however many seeds have sprouted by 10, and that's your germination rate (2 seeds equal 20 percent, 5 seeds equal 50 percent, etc.). If your germination rate is less than 70 percent, you can always still plant those seeds in your garden—just sow them more heavily than you normally would. If your germination rate is less than 50 percent or so (or if the seedlings that emerged seemed stunted), I recommend starting over with fresh seeds.

Seeds that sprouted during your germination test can, of course, carefully be transplanted to your garden.

How to Store Seeds Properly so They Last as Long as Possible

Just as important as seed quality and seed type in a seed's life expectancy is how that seed is stored. Overall, seeds will last much longer if they are stored in a cool, dark, and dry place. In other words, you want to protect your seeds from heat, direct sunlight, and moisture (to prevent mold or pre-mature sprouting).

As soon as you're done planting seeds in the garden, make sure to move any remaining seeds back inside, out of the sun. Then store them properly.

Seed Storage Location

A good option for a cool, dry, low-light place might be your kitchen pantry, a kitchen cabinet, a closet, or a drawer in your home office. A spot in your basement could also work if it's low humidity.

Seed banks are kept cold, but you don't have to turn your own home into an unpleasant environment for humans for the sake of your seeds. Just aim for a consistent temperature. With that in mind, garages and sheds are not ideal storage locations.

Seed Storage Container

Keep reducing humidity in mind when you're picking a storage container for your seeds, as well. Jars, tin containers with clear tops, sealable seed packages, and repurposed spice shakers are all great options. If you use a plastic bag, throw in some rice or one of those little desiccant packs that come in shoe boxes and new purses to absorb excess humidity.

If you're using seeds envelopes or plastic bags, store these inside an airtight container. I've used a recipe card box, a metal toolbox, and a box made from cedar fence planks. Consider writing the date of expected expiration on each seed packet.

How to Prevent Having a Bunch of Seeds That Expire

In addition to storing seeds properly, reducing the overall number of seeds that you buy and buying high-quality seeds also ensure you don't end up with a bunch of duds, so to speak.

The best way to reduce the number of seeds you buy (and the cost!) is by ordering seeds with a gardening buddy (or two or three). Seed packages often contain hundreds of seeds, and you're unlikely to ever need even half that many seeds for plants that take up a lot of room in the garden and/or that spend a long time growing.

Take the seed package of kale I just got. Let's say the package contains 100 kale seeds (even though that's conservative). I can only fit about 10 mature kale plants in my raised beds. Even if I grow 10 kale plants every year over the next 5 years, that's still only half the package of seeds used up before they're likely to no longer be viable.

Seed companies don't create seed packages with kitchen gardeners in mind. They fill these packets for farmer-gardeners with row gardens or homesteaders with room to plant hundreds of things at once.

So instead of spending $5 on a package and only using 20 percent of those seeds before they expire, you could have a little garden party with your friends, and you could each end up with only the seeds you need for a fraction of the price.

This is perfect for seeds for plants like tomatoes, peppers, and squash—anything that you can only plant a limited quantity of in your space. Other things, like salad mixes, are better to purchase by yourself because you probably will use up the entire pack, perhaps even in one season.

Where to Buy Seeds That Will Do Well in Your Garden

Seeds are incredible, but please believe me when I say that not just any seed will do. I used to grab seed packages from those tempting displays on my way out of hardware stores, and even though I had great soil and followed all of the instructions for plant spacing and depth, I just wouldn't get great rates of germination.

It wasn't until a friend recommended ordering seeds from a heritage seed company that promised naturally and organically grown seeds that I finally learned my lesson. Buy the good stuff. Seeds are some of the cheapest purchases you'll make for your garden anyway, so spend a couple extra bucks for quality. I mean, unless you like being disappointed.

Remember this when buying seeds:

• find seeds as locally sourced as possible so that they're better adapted to your area
• prioritize seeds that are organically produced

It can be hard to find seeds that are really "certified organic," but it's worth the effort. Seeds from plants that were heavily sprayed with insecticides and fertilizers during their growing cycle end up being negatively effected.

Some of my favorite companies for organic seeds include Baker Creek, Botanical Interests, Johnny's Selected Seeds, High Mowing Seeds, and Southern Exposure Seed Exchange. 

Hope This Helps You Enjoy Seeds for Your Garden for Seasons to Come

It's hard to garden for several years and not come to find each and every little seed an absolute astonishment. Keep in mind that your seeds are living things, store them properly, and watch the miracle that is germination in your garden over and over again, season after season.

Thanks for helping me make gardening ordinary once more!