Ive grown them even here in our very short growing season. Thry aren't difficult to grow if you can keep the weeds under control over the 3 1/2 -4 months tgey take to mature.
I've found that the easiest way to harvest them is to pull the plants by the roots when most of the pods are dry or drying well. Hang them upside down in an airy spot to finish drying. Then strip the pods off and put them into a feed sack (or an old pillowcase for non-farmers.
Tie the neck of the sack closed snugly... put on some music, and stomp the sack! After a few minutes, shake it up and stomp some more. If they were fully dry, the pods will shatter and leave clean beans. The beans are heavier than the chaff, so if you cut a corner off the bottom of the bag, you can pour most of the beans out without a lot of trash coming along. Then winnow the beans (and dump the chaff/trash into a pail and stir it around to find any beans you missed.
There are some amazing heirloom varieties of dry beans... our favorites are Jacobs Cattle, Calypso (there are several names for them.. they are the black and white "yin and yang" bean) and one callet the .Hutterite Soup Bean. All will ripen in our short season, and the Hutterite soup beans make the smoothest, creamy bean soup.
Check out Seed Savers Exchange for some really neat varieties.
Summerthyme