It's a good idea, if you start your own seeds, to do a thorough cleaning out of the seed supply every year. Keeping old seed around will just lead to frustration. Here is a basic guideline for seed shelf-life:
- 1 year: onions, parsnips, parsley, salsify, scorzonera, and spinach;
- 2 years: corn, peas, beans, chives, okra, dandelion;
- 3 years: carrots, leeks, asparagus, turnips, rutabagas;
- 4 years: peppers, chard, pumpkins, squash, watermelons, basil, artichokes and cardoons;
- 5 years: most brassicas, beets, tomatoes, eggplant, cucumbers, muskmelons, celery, celeriac, lettuce, endive, chicory.
I am never too sure about what to do with old seeds. Sometimes I throw them around on bare patches of earth to see what will come up and other times I sadly throw them into the compost or trash. Most importantly, I try to be really careful to order only what I can use within the lifetime of the seed.