Every gardener has one – a motley collection of faded, tattered, half-used packets of seeds, with the contents all past (sometimes well past) their sow-by date. They clutter up the "anything" drawer, get more out-of-date by the year, and still we hold onto them! I put it down to that natural thriftiness that every serious gardener seems to have. That, and the fact that we're usually behind schedule when it comes time to sow, and not willing to chance the risk of old seed failing to germinate. The result? We buy new packets of seed - and still hang on to the old ones!
So, should you biff those tattered old out-of-date packets? No, not yet! Once the fever of spring and early summer sowing is over, and while there's that small hiatus before you start thinking about what has to go in the ground for winter, allow yourself the luxury of a little unhurried experimentation. If you're not a natural "labeller", now is the time to get out the permanent marker and cut the yoghurt pottle into strips. Scribble down on each platic strip the name of the old seed and the date you're sowing it. Then, take a small pinch of seed from each packet and sow it into a container of good quality potting mix. Give your test seeds the best possible conditions (they're old and tired and will perform best if kept warm and moist). And don't rush them - older seed can take a week or more longer to germinate than fresh seed (I recently sowed Brussels Sprouts that were 4 years past their sow-by date and, after 3 weeks, a reasonable percentage of the sample germinated!).
If, after a generous amount of time, the seeds come to nothing, toss the rest of the packet out. If they're viable, label the packet accordingly, confident that the seed will germinate if you use it within a few weeks. Then it's time to pat yoursef on the back for having saved all that money. In fact, I'd say you've earned yourself a trip to the garden centre for a flat white, and that rose you've had your eye on for a few weeks!