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Are old seeds still good?
Every gardener finds an old seed packet at the back of a drawer and wonders whether it is worth sowing. Throwing it away wastes seed that might still sprout well, but sowing dead seed wastes a whole bed and weeks of the season. This estimator gives an honest first answer from three facts you already know: the seed type, how old it is, and how it was stored. It is an educational estimate from typical seed life, not a lab test, but it is far better than guessing.
Seed types age at very different speeds. Tomato and cucumber seed often stay useful for five years or more, while onion and lettuce seed fade fast, sometimes within two or three years. Beans and peas sit in the middle, usually good for three to five years. These differences come from seed chemistry and seed coat thickness, and they are consistent enough that seed guides publish typical life spans. The estimator uses a decline rate per type, so an old onion packet scores much lower than an old tomato packet of the same age.
A worked example
Take tomato seed three years old, stored cool and dry. The estimator starts near 95 percent and subtracts a small yearly decline adjusted for cool storage, giving about 87 percent. That is a clear green light: sow normally, perhaps with a few extra seeds. Now take onion seed five years old, stored warm or damp. The decline is steep and the storage factor is harsh, so the estimate falls to zero. That packet is not worth a bed, though a quick paper test could still surprise you.
A middle case shows why the estimate helps planning. Lettuce seed three years old at room temperature lands around 59 percent, a fair verdict. You would not throw it away, but you would not sow it thinly either. Sow extra, thin later, and perhaps run a small paper test first. The verdict words matter here: good means sow normally, fair means sow extra and test, and poor means replace the seed or sow very thickly and test first.
The ten-seed test beats any table
When the estimate is in the fair range, run a real test. Put ten seeds on damp kitchen paper in a covered tray, keep them warm, and count sprouts after the normal sprouting time. Seven sprouts suggest about 70 percent, three suggest about 30 percent. The test costs ten seeds and a week, and it tells you about your actual packet, not an average packet. Use the estimator to decide which packets deserve a test, and the test to decide how thickly to sow.
Do not confuse viability with vigour. A seed can sprout yet still make a weak seedling that grows slowly and never catches up. Old seed often loses vigour before it loses the ability to sprout at all, so seedlings from old packets may look thin even when the count looks fair. If you need strong plants for a short season, fresh seed is worth the small cost, even when the old packet still sprouts.
Storing seed well from now on
The best storage is cool, dry, dark, and sealed. A paper envelope inside a sealed jar with a small silica gel packet, kept in a fridge, is excellent for most home seed. Label every packet with the seed type and the year you bought or saved it, because memory fades faster than seed does. Avoid storing seed in a greenhouse, a loft that bakes in summer, or a damp shed, since heat and damp together are the fastest way to kill seed.
Remember that these garden results are general guidance estimates only. Your local climate, soil, weather, and storage history govern the real answer, so treat the percent as a planning guide and confirm with a test when the stakes are high. A packet that scores fair is not a failure: it is a packet that needs a test and a thicker sowing, and many fair packets still give a good crop.
Frequently asked questions
Can dead-looking seed come back? No. Once seed viability is gone, soaking or special treatments will not restore it. Soaking can help hard-coated seed sprout faster, but it cannot revive dead seed.
Should I sow poor seed very thickly? Only if the seed is rare or you have nothing else. Thick sowing of weak seed gives uneven, weak plants, and thinning costs time. Fresh seed is usually cheaper than the lost weeks.
Does freezing seed help? Freezing dry seed can extend its life, but freezing damp seed kills it, because ice damages the seed. Only freeze seed that is fully dry and sealed, and let it warm up before opening the jar, or condensation will wet it.
Use the estimator above with your seed type, age, and storage, run a ten-seed test when the verdict is fair, and sow extra when the estimate is below 70 percent. Old seed deserves a test, not a guess.
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