But in the winter, when the snow is flying, and you can only entertain faraway dreams of rototilling and planting seeds, you will be glad that you did insult those greens. Canned or frozen greens can be made into some delicious meals when fresh greens aren't available.
There are a number of good resources for home canning. The USDA Complete Guide to Home Canning is always up to date, and it's free. It is available online here. With one keystroke you can find instructions about how to can anything, including spinach and other greens. It also provides guidelines for processing foods at your altitude, whether you use a weighted-gauge or a dial-gauge pressure canner. This resource is comprehensive and easy to understand. I would never be able to out-do those people on this little blog. I would rather focus on sharing ideas and recipes using your homegrown foods here.
Incidentally, freezing greens is at least as good as canning them, if not even better. And it's easy. The pretty green colors are certainly maintained better by freezing than by canning. But this year I am canning more greens than I am freezing. I just want to save room in the freezer for some other things. If you prefer to freeze yours, remove tough stems, wash thoroughly, blanch or steam for just a couple of minutes, cool quickly in ice water, drain, and vacuum pack or put into freezer bags or freezer containers.Since a variety of fresh greens (and other colors!) are still thriving right now, we continue to enjoy them straight from the garden. So I'm not going to use the canned or frozen ones just yet. But I know I won't be sorry that I saved some before the heat of summer causes them to bolt. You won't be sorry if you can or freeze some, too!