To vine dry beans (navy, kidney, butter, great northern, lima, lentils and soybeans) leave bean pods on the vine until the beans inside rattle. When the vines and pods are dry and shriveled, pick the beans and shell them. No pretreatment is necessary. If beans are still moist, the drying process is not complete and the beans will mold if not more thoroughly dried. If needed, drying can be completed in the sun, oven or a dehydrator. Pasteurization is needed for those beans dried entirely in the sun.
Source: MSU Extension