You probably planted either Kentucky Blue or Kentucky Wonder pole beans. These two varieties are used primarily to cook as green beans without shelling. The Kentucky Blue pod reaches 7 inches in length and the Wonder pod is 9 inches long when ready for harvest.
Harvest the pods when they are firm, crisp, and fully elongated but before the seed inside has developed (before it bulges out the side of the pod). Pick when the beans are dry to avoid spreading disease.
If some of the pods grow to the point where the seeds inside are fully developed, let those pods remain on the vine until dried. Then harvest and shell them to make baked beans.
