I live in MA and I find that you only need to grow it once. It seems to prefer cooler weather. When our hot summers come, it bolts and goes to seed. When this happens, I just plant the seeds in a small , slightly shaded, section of my garden bed and they sprout in time for fall picking.

They seem to tolerate quite cold temperatures, and one year I was still picking it into late November after many nights of temperatures in the 20's.

This spring the plants came up in profusion and they are apt to pop up anywhere, so I know I'll have plenty for cooking.

If I have too much, I just take a bunch and make a quick pesto of the leaves and a little olive oil using my small food processor. Then I just pack it in small sandwich bags, flatten them out and freeze. Then, throughout the winter I just break off a chunk or two to use in whatever dish I'm making.