How Long Do Seeds Last? Here’s What You Need to Know

As you thumb through half-empty seed packets left over from last year, or even several years ago, you wonder if they’re still good.

You shrug, plant the seeds, and cross your fingers. If they don’t germinate, you’ll buy some new ones.

Here’s my prediction. By the time you notice the seeds haven’t germinated, your garden will be several weeks behind where it should be. And that’s not good. It’ll stop you from getting the most out of your garden this year.

But you can easily avoid this mistake. Keep reading to find out how.

Are Your Old Seeds Viable?

The question to ask yourself when planting old seeds is, are they still viable?

In other words, are your seeds still alive, and will they germinate?

You can do a simple germination test to find out. (See tips below for testing your seed germination rates).

But a germination test won’t tell you whether they’re vigorous enough to reach maturity and give you a good harvest. Agricultural labs test for seed vigor, but it’s not something we home gardeners can do accurately.

Even so, if you do a germination test of old seeds and the seedlings seem stunted (smaller than normal leaves or root systems), it’s probably time to start over with new seeds.

What Affects Seed Viability?

Three things will determine whether your seeds are still viable.

1. Age of the seeds. All seeds will be viable for one to two years. After two years, germination rates will drop for many types of seeds, and will eventually fall to zero. So, stocking up on seeds ‘for an emergency’ isn’t a good idea, because they don’t last forever.
2. The type of seed. What type of seed you have will also affect how long it’s viable. Some seeds like onions and corn have a short lifespan, while others like cucumber and melon can last up to 6 years. Pelleted seed is best used within one year because the pelleting process can reduce the seed’s lifespan.
3. Seed storage practices. Seeds stay viable much longer when you store them in a cool, dry, dark place. Reducing humidity is key. This can be as simple as storing seeds in a sealed plastic bag with some rice or desiccant packets to absorb excess humidity. Store the bags in a cool, dark place.

Every time a seed experiences less than ideal conditions, its longevity and viability decline.

Even though they appear lifeless, seeds are living things. So, how you treat your seeds out in the garden is important. Don’t leave them lying outside to bake in the hot sun, or let them get wet. And don’t leave them in your greenhouse or shed.

If you always put your seed packets away when you’re done with them, your seeds will last longer.

So, How Long Do Seeds Last?

Here are some general guidelines. Your seeds’ shelf life depends on how carefully you’ve stored your seeds.

Pro tip: Save time by writing the expected expiration date on your seed packets. Then you won’t have to spend time every year deciding whether your seeds are still good.

Seeds that remain viable for up to 5 years:

• Beets
• Broccoli
• Brussels Sprouts
• Cabbage
• Cauliflower
• Celery & Celeriac
• Cucumber
• Eggplant
• Kale
• Lettuce
• Melon
• Most Perennial Flowers
• Peppers
• Pumpkins
• Radish
• Rutabaga
• Spinach
• Squash & Gourds
• Swiss Chard
• Tomato
• Turnip
• Watermelon

Seeds that remain viable for up to 4 years:

• Artichoke & Cardoon
• Asparagus
• Beans
• Carrots
• Mustard
• Peas

Seeds that remain viable for up to 3 years:

• Asian Greens
• Corn, Sweet
• Most Annual Flowers

Seeds that remain viable for 1-2 years:

• Leeks
• Okra
• Onions
• Parsnip
• Rhubarb

Testing Seed Viability

If you’re uncertain whether your old garden seeds will germinate, you can do a germination test.

Download Your Free Seed Viability Chart

This chart covers seed longevity for more than 100 types of vegetables and flowers! Here’s a sneak peek of the chart that answers the question, how long do seeds last?

Want More Help With Seed Starting?

If you liked this article, you’ll love my post about setting up grow light shelves.