Here Ruth gives us her top tips on seed saving from her Phoenix Urban Growing Course.
Some seeds need to be fermented before being dried, for example tomatoes. This process ensures germination. Keep them in a jar of water for a few days. Rinse well and dry. [Garden Gnome adds: Actually a really easy way is just to squish the tomato onto kitchen paper and let it dry thoroughly, you can pop the paper onto a seed tray of compost next early spring, cover with a thin layer of compost, keep warm and moist and you will have a perfectly serviceable crop.]
All seeds to be dried should be thoroughly cleaned first, and the chaff and the unviable seeds sieved or removed before proper drying. In the case of broad bean seeds, they should be visually inspected for holes, and later stored in a freezer in order to kill any possible insect infestation.
During ripening and drying on the plant, the seeds prepare for dormancy by converting sugars to more stable fats and starch. After that they can be safely dried and stored. Drying should be gradual and thorough, shady spot, airy, dry (20% to 30% Relative humidity), for a couple of weeks, relatively to the size of the seeds. One easy way is to place the seeds in a jar of dry rice for a fortnight. The rice will gradually dry up the seeds. Dry corn and beans will shatter when hit with a hammer.
Storing should be in dry, constant temperature and moisture, in an insect-free environment. You can store them in the fridge, or even a freezer, but gradually bring them back to room temperature before sowing.
Best not to swap squashes and pumpkin seeds (Cucurbits), unless the plants have been well isolated, as they cross-fertilize very easily, being a promiscuous lot! Use new stock of seeds instead.
Some seeds can keep for several years, under favourable conditions, however, some, like parsnips, only keep for a year. Best to use seeds collected this year. Old seeds can always be used for a spot of guerrilla gardening.
Check out Seedy Sunday’s excellent website for more information on all things seedy. (Adapted from Seedy Sunday’s website)