Seed Lifespan

If you’re a gardener who saves seeds or buys in bulk, proper storage is key to keeping them viable for future planting seasons. Seeds are living organisms, and how you store them determines how long they’ll last.

Why Storage Matters:

Humidity and heat are the biggest enemies of seed longevity. Moisture causes seeds to deteriorate quickly, and high temperatures speed up aging. Ideally, seeds should have a moisture content of no more than 10–12% and be stored in a cool, dry environment.

Pro Tip: The sum of temperature (°F) plus relative humidity (%) should never exceed 100. For example, if your storage area is 50°F, humidity should stay below 50%.

Best Practices for Seed Storage

• Keep seeds dry: They should feel brittle before storing.
• Use paper envelopes: Label with seed type and year, then place in an airtight container.
• Store in a cool, dark place: A refrigerator or freezer is ideal. Freezing can extend seed life for 10 years or more—just make sure seeds are thoroughly dried first.
• Avoid warm, humid spots: Never leave seeds in a greenhouse or sunny windowsill, even for a few hours.

How Long do Seeds Last?

Most vegetable seeds remain viable for 2–3 years, but some last much longer. For example, lettuce can sprout after five years, while onion seeds typically last only one year.

Here’s a quick reference guide for average storage life under proper conditions:

Testing Seed Viability

Not sure if your old seeds are still good? Try a simple germination test:

1. Moisten a paper towel (damp, not dripping).
2. Place 10 seeds in a row and fold the towel over them.
3. Seal in a plastic bag, label with date and seed type.
4. Keep in a warm spot (around 70°F).
5. Check daily for moisture and sprouting.
6. After 7–10 days, count how many seeds germinated.

Interpreting Results:

• 70–90% germination: Seeds are usable; sow a little thicker.
• 100% germination: Excellent! Ready to plant.
• Less than 70%: Consider replacing with fresh seed.

(You can plant the sprouted seeds from your test—just cut the towel around each seed and plant it paper and all.)