Seed dies of three things: warmth, damp and time. Storage is just defending against the first two so the third takes as long as possible — and it's mostly a biscuit tin's work.
An unheated room, a north-facing cupboard, a shed that doesn't freeze-and-cook in cycles: anywhere steady and cool beats anywhere warm. Paper packets inside an airtight tin is the classic combination — paper lets seeds breathe, the tin blocks damp and mice, who read seed labels better than you'd think. A tablespoon of dry rice (swapped occasionally) or a silica sachet from a shoe box handles residual moisture. The fridge works too, in a sealed jar, if the household treaty allows.
| Keeps 4+ years | 2–3 years | Sow fresh-ish |
|---|---|---|
| tomatoes, cucumbers, brassicas, lettuce | beans, peas, squash, chillies, beetroot | parsnips, onions, leeks, sweetcorn |
Stored well, many seeds outlive these guides — stored on a sunny windowsill, almost nothing does. The year on the packet is what makes this table usable; an undated packet is a shrug in envelope form.
For anything old or precious, test before you rely: ten seeds on damp kitchen paper, in a bag, somewhere warm, a week or so. Eight sprout, sow normally; four sprout, sow double; none — a moment's silence, then order fresh. Ten minutes in February beats an empty seedbed in April, every time.
Once a year — seed-ordering season is natural — go through: date-order the packets, test the elderly, cull the hopeless, and list what needs replacing before the spring rush. A tin of clearly labelled, dated, tested packets is the closest a gardener gets to money in the bank.
General gardening guidance, August 2026. CAAC.