sam wrote:

hi, how long should you keep seeds? I've just planted some tomato and
aubergine seeds from packets I got 2 years ago, don't know if they'll grow,
should I buy new ones? TIA

Assuming that you keep them cool and dry 5 years is usually fine for
most seeds. If you let them get wet and warm then they may fail.

Although I have had courgette seeds that were stored carelessly in
packets that were rained on and fell apart the seeds remained viable
afterwards (not a recommedended technique).

Compost is cheap enough and either the seeds will grow or they won't. We
discovered some old WWII era allotment seeds at my secondary school kept
in the back of a cupboard. Most grew away perfectly well after a few
decades dormancy.

Decades is not uncommon and some seeds will remain viable for hundreds
of years. Poppy is probably one of the most well known seeds with very
long life even in buried in damp soil. The Kew seed bank is aiming to
keep seeds for considerably longer by manipulating the conditions.

Regards,
Martin Brown