Found a half-used packet of pepper seeds from a few years back and wondering if they're still good? Don't guess! A simple germination test takes about a week, costs nothing and tells you exactly how well your seeds will sprout. In this guide, you'll learn how long seeds typically last, how to test them at home and what to do with the results.
How long do seeds stay good?
Seeds are alive, and they slowly lose vigor over time. How fast depends on the crop and how they're stored. Kept cool, dark and dry, typical ranges are:
- 1 to 2 years: Onions, leeks, parsnips, chives and sweet corn.
- 2 to 3 years: Peppers, beans, peas, spinach and carrots.
- 3 to 5 years: Lettuce, kale, broccoli, cabbage, beets and squash.
- 4 to 6 years or more: Tomatoes, cucumbers, melons and radishes.
These are just guidelines. Older seed often still sprouts, just at a lower rate. A test tells you for sure.
How to do a paper towel germination test
- Dampen a paper towel. Wet it, then wring it out so it's moist but not dripping. Too much water can rot seeds.
- Count out 10 seeds. Ten makes the math easy. Spread them on half the towel so they aren't touching.
- Fold and bag it. Fold the towel over the seeds and slip it into a plastic zip-top bag. Leave it slightly open for a little air, or open it briefly each day.
- Label it. Write the variety and date on the bag.
- Keep it warm. Set the bag somewhere warm, about 70 to 80°F, but out of direct sun. The top of the fridge often works.
- Check daily. Look for little white roots. Keep the towel damp.
How long should you wait?
Give seeds at least their normal germination time. Many vegetables sprout in 5 to 10 days. Slower seeds like peppers and parsley can take 2 to 3 weeks, so be patient before you count.
How do you read the results?
- 8 to 10 sprouted (80 to 100%): Great seed. Plant as usual.
- 5 to 7 sprouted (50 to 70%): Still usable. Sow a little more thickly, or plant 2 to 3 seeds per spot and thin later.
- 4 or fewer sprouted (40% or less): Seeds are getting weak. Sow very thickly if you want to use them up, but for important crops, it's worth getting a fresh packet.
Bonus: if the sprouted seeds are big enough to handle, like beans, squash or peas, you can gently plant them in pots instead of tossing them.
How do you keep seeds fresh longer?
- Keep them cool: A closet or the fridge is far better than a garage or shed.
- Keep them dry: Store packets in an airtight jar with a silica gel packet.
- Keep them dark: Avoid windowsills and greenhouses.
- Label everything: Write the year on each packet so you know which to use first.
Our seed packets are mylar-lined and heat-sealed to protect seed until you open them, and I pack every one myself here in Minnesota.
Restock the short-lived seeds
If your test shows some seeds are past their prime, start with the short-lived crops. These are good ones to buy fresh each year:
- Yellow Sweet Spanish Onion (about 110 to 120 days): a big, mild, long-day onion for northern gardens.
- Harris Model Parsnip (about 110 to 120 days): smooth, sweet roots that get even sweeter after frost.
- Chives: an easy perennial herb for the garden or a windowsill pot.
Test now, plant with confidence
A quick test this winter saves you from empty rows in spring. Grab a paper towel and some old seed packets and give it a try. All our seeds are non-GMO and USA grown.
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