I harvested our kidney beans today. It was just a matter of letting the pods dry out on the plants by themselves and once the plants have mostly died off open the pods and collect the beans. The beans will last a long time like this in a container or bag (you can freeze them) we keep ours in the cupboard. Some can be put aside to grow new crops or throw a handful in a soup or casserole for a healthy addition to a meal - there's no need to re-hydrate as they will do this during the cooking process. The kidney bean plant is a small bush bean about 40 cm tall so it's very compact and easy top grow in containers or small spaces.