While gardeners grow a number of varieties of beans, the bush and pole types of the string or green bean is the most common. These beans produce a pod that is harvested before maturity for use green or allowed to mature for dry beans. In the case of dry beans the seeds are removed from the pods.
In some circumstances bean plants bloom but fail to set pods. Common causes include excessive nitrogen fertilization or warm conditions with low humidity. Fertilize after the first harvest to avoid over fertilization although the weather is often outside the gardener's control.
Harvest the beans about two weeks after the full bloom. Actual harvest may dates vary depending on weather and other factors. Bean plants continue to bloom as long as the pods are harvested before maturity. This results in an almost continuous cycle of blooms and harvests. Harvest about once a week to gather the pods at the proper size. The harvest cycle occurs more frequently than the length of time from bloom to harvest because not all plants will be at the same maturity point.
Harvest by hand working carefully to avoid breakage to stems and other blossom bearing structures. Avoid harvest during times the plants are damp or wet with rain or dew. This can spread diseases within the bean plants.
As long as the pods are harvested before maturity the plants will continue to develop blooms and pods until the plant is killed by fall frosts. The cycle of harvestable beans two weeks after the full blooms continues through the summer.