Beans are a versatile plant in the vegetable garden. There are tall vine varieties and smaller bush types. You can grow edible pod green beans or hard, shelling varieties such as kidney beans. Bean are a warm-season legume that produces either edible seeds, edible pods or both. Understanding the properties of a bean plant is necessary if you want to grow these abundantly producing vegetables in your garden.
Vegetable plants require nitrogen in the soil in order to produce their green leaves and healthy fruit. Unlike other vegetables that require that nitrogen is already present in the soil, bean plants have the interesting property that allows them to create their own nitrogen in the soil. A bacteria in the soil, called rhizobium, adheres to the bean's roots and brings in nitrogen from the air for the beans to use. While this bacteria is already present in many soils, most bean seeds are treated with the bacteria prior to planting. This property is beneficial because bean plants require very little if any additional fertilizer to thrive.
Beans are classified as either a vine or a bush. Vine varieties may reach heights of 6 feet or more if they are given the proper trellis or support to twine up. Vines twine clockwise around the pole or trellis, requiring no tying or help from you to find their way. Bush varieties are not nearly as tall. Instead, they grow on compact plants. Bush types are well suited to container growth because of their smaller size and upright property. There are also half-runner varieties that are only 3 feet long and can be grown either on supports or sprawling in the garden.
All bean plants flower. Varieties like the Scarlet Runner bean produce large, vibrant flowers that are grown as an ornamental as well as an edible plant. Flowers range in color from white to red, but most have a yellow spot near the center to help attract insect pollinators. Beans produce both male and female flowers on each plant, so multiple plants are not necessary for pollination.
All beans produce seeds within pods. Tender beans are called snap or green beans, though not all are green. These are harvested when the pods are fully grown and tender, but before the seeds begin developing and swelling in the pod. Shell beans are harvested once the bean seeds inside are fully mature and dry, after the pods have browned and dried on the plant. Most tender bean varieties can be left on the plant and harvested as shelling beans if desired.