Depending on your particular climate, there are many non-perennials that you need only plant once to harvest year after year.
Here in Zone 5/6, this is what we are working on:
These are biennial vegetables, meaning they produce roots and leaves the first year and flowers the next.
We overwintered our parsnips and after harvesting this spring, left a few to flower. We expect, as other gardeners have assured us, that the flowers will then turn to seed and grow more parsnips to be harvested next spring.
Cousins to parsnips, the same principle holds true. Carrots are more difficult to winter over, so we will heavily mulch just a few that will be left in the bed to see if we can pull it off. These methods are also a good way to collect seed, so if nothing else you can try that.
3. New Zealand Spinach
Not a true spinach, but one that is used the same way. This particular variety does not bolt as fast as spinach does, but when that happens it will also reseed.
We expect to see it coming up next spring as well.
4. Tomatillos and Chokecherries
Similar but not the same, these two relatives of tomatoes also will reseed and offer you many new plants for next season. We are going to cover this bed with plastic late in the winter, to help them get a faster start.
"What??" you may be thinking.
At least, that was our reaction.
But many a gardener has told us that they bring in a potted sweet pepper plant before the frost, and store it in a cool room or basement.
They say it goes into a dormancy period, and will spring back to life when the weather warms back up.
So this we had to see for ourselves, and have a beautiful Lady Bell just for that purpose.
Of course the results of all these examples, that others swear by, will be shared here with you.
Why not give some a go?
You might be pleasantly surprised.