Wrapping up this 4-part series on seed saving, this last post focuses on how to save seeds that, over a few years, become adapted to the hyperlocal microclimate of your own yard.
Adapting seeds to your neighborhood is the same process humans have used for millennia to cultivate varieties that gradually become tastier, more prolific, and more resilient.
Each growing season, watch your plants carefully and notice how each plant of the same variety grows a little differently. Of course this could be due to environmental factors -- one spot gets more or less water or sun, perhaps there's an extra good pocket of soil that you can't see, who knows? But all things being equal, there's still another factor: Even seeds from the same variety have ever-so-slightly different genetics and characteristics.
The gardener's job is to encourage the genetic variations that thrive in their own soil and climate by saving seed from the plants that do best.
Depending on your preferences, you may select for the best tasting, the most prolific, the most drought tolerant, or whatever is important to you. Over several generations (plant generations, that is) the subtle changes will accumulate, and your plants will become more and more locally adapted.
One of the reasons we work with small, independent seed growers like Redwood Seed, San Diego Seed, Living Seed, and Hudson Valley Seed is that they are all highly skilled plantspeople who select seed every year that adapts to the widest variety of conditions possible, given their locations. All of them (including all the seed we sell), along with most of the hundreds of small, local seed companies around the country, provide excellent seed to use as the starting point for your home seed-saving adventures.
Here are two examples of seed I'm saving this year, selected for very local reasons:
First is this tomato volunteer that's growing, thriving actually, completely un-irrigated in the packed clay of a path. That's one tough tomato! Because it's quite a bit behind its irrigated cousins in the veggie beds, I haven't tasted the tomatoes yet. But if they pass the taste test, this one will be a keeper.
Another example are these two arugula plants just beginning to flower. They're the last two of the ten I planted in the spring. All ten were from the same seed packet, and yet these two bolted about a month after the other 8. The seeds and seedlings of that batch were all treated the same way, and they were grown together in the same spot. As far as I know all 10 plants had more or less the same growing conditions. But two of them lasted a lot longer! And so those are the two I'll use for seed saving.
One final note before the end of this series. If you plan to save seed long term to sell or trade, you must also consider population sizes. If you only ever grow and save seed from one zucchini plant a year (and honestly, one healthy zucchini plant is enough for most families!), over time the plants will become inbred and loose their genetic diversity and vigor.
You've probably heard about zoos and endangered animal conservation programs concerned with breeding population numbers. The same goes for plants. You can refer to this chart for the population numbers required to maintain a variety indefinitely. Those numbers are for commercial growers. Home gardeners can get away with a lot less. But still, it's a good idea to keep in mind, especially if you're interested in long-term food security.