How to Test Old Seeds for Viability
Test old seeds with the paper towel method: 10 seeds, damp towel, 7 days. 7+ sprouted = viable. 3–4 = plant thick. 0–2 = dead.
The same test commercial growers use. Costs nothing.
The Method
- Count 10 seeds.
- Dampen paper towel.
- Place seeds 1 inch apart.
- Fold towel over.
- Put in ziplock bag (slightly open).
- Warm spot (70-75°F).
- Check daily. Keep damp.
Reading Results (Day 7)
| Sprouted | Viability | Action |
|---|---|---|
| 9-10 | 90-100% | Plant normally |
| 7-8 | 70-80% | Plant thicker |
| 5-6 | 50-60% | Plant 2x density |
| 3-4 | 30-40% | Not worth it |
| 0-2 | Dead | Discard |
Seed Shelf Life
| Variety | Years |
|---|---|
| Beans, peas | 3-4 |
| Tomatoes, peppers | 4-6 |
| Lettuce, kale | 3-5 |
| Carrots, onions | 1-2 |
| Parsley, parsnip | 1-2 |
Common Questions
Can I test without a paper towel? Yes, but you waste weeks if dead.
How long does it take? 5-10 days.
Should I test every packet? If over 2 years old.
What temperature? 70-75°F.
Can I plant sprouted test seeds? Yes. Carefully.
Does the test damage seeds? No.