There've been some questions about green beans recently, so here's the skinny.
Some varieties of beans are best put by in the freezer, while others handle the canning process quite nicely. Be sure to read the seed catalogue descriptions, when you are planning your garden, so you are not disappointed with the final product. Vesey and Burpee are good about that, and both companies carry varieties that do nicely with short seasons.
Canning does not improve the quality of the food put by. If beans are past their prime, they’re not going to get any better by dumping them in jars and pressure cooking them. You’ll have much better results, if you can beans that are slightly immature.
Because green beans are low-acid, they must be pressure canned to ensure safety. At our elevation (about 3,000 feet),that means 20 minutes for pints, 25 minutes for quarts at 12 pounds pressure. You do have choices, as to hot or cold pack and whether to salt or not, and that is nice. Salt is only added for taste, not to preserve. You may can beans whole (tip and tail them first) or cut into one inch pieces for convenient additions to soups and stews.
For hot pack, cover beans with boiling water. Boil 5 minutes. Pack loosely in canning jars; add salt, if desired. Cover with boiling cooking liquid. Leave one inch head space.
For cold pack, pack tightly in canning jars; add salt, if desired. Cover with boiling water.
Processing time is the same for both methods.
Remember to vent your canner properly to be sure your foods are safely processed. Air trapped in a pressure canner lowers the temperature inside the canner. To vent a pressure canner, allow steam to escape steadily from the petcock for ten minutes, then close the petcock or put the weighted gauge on the canner.