FarmerDill wrote:

Cultivars, specifically designed for snap beans, have a meatier pod, while those
used for dried beans typically have a thin pod which quickly gets tough and
stringy. That squash will probably surprise you. They are usually a shorter
season than for instance the black turtle bean you mentioned. Expect the squash
to ripen before the turtle beans are ready to be picked as shell beans.

This makes a lot of sense. In the past, unless I caught the green beans when
they were very small, they did get tough. This year I'll buy seeds specifically
for green beans. I've never grown beans as shell beans. Usually I plant them
when I have a bit of extra space and want to see something growing there fast.
Green beans are perfect for this. Instant gratification (nearly).

--Lia