Beans are members of the legume family. Legumes are plants that produce seed pods that split into two halves to release their seeds. There are three main types of bean plants--climbing or pole beans, broad beans and bush beans. Climbing beans need support for the long, trailing stem, with some varieties reaching 8 feet in height. Bush beans and broad beans generally support themselves, but bush beans may need straw around the base to prevent the pods from rotting if they are resting on the earth.
Seeds and Seedlings
All types of beans should be planted at a depth of 1 to 1 1/2 inches. To increase the speed of germination, it is advisable to presoak the seeds in water for 12 to 24 hours. Bean seeds consist of a hard, dry, protective outer layer, concealing and protecting two cotyledons. The cotyledons are the two halves of the seed that provide nutrients to the seedling as it grows. As the seedling grows, the cotyledons shrivel, as the nutrients they contain are used. The roots of the seedling develop quickly, meaning the roots are able to absorb nutrients and sustain the seedlings by the time the cotyledons die.
The fruit produced by bean plants is nutrient rich. The U.S. Department of Agriculture (USDA) states that 1 cup of raw green beans contains 37 mg of calcium (Ca), 1.03 mg of Iron (Fe), 211 mg of potassium (K), 12.2 mg of vitamin C and 35 mg of vitamin A, among others. Beans are also rich in fiber and protein, which is why they appear in both the vegetable and meat groups of the USDA’s “MyPyramid” food groups.
It is very difficult to save seeds from broad beans, as they cross-pollinate very easily, which can lead to unstable hybrids with inferior fruit, or a reduced yield. To save seeds from broad beans without cross-pollination, it is necessary to ensure that only one variety is grown in a half-mile radius, which is not practical for most home gardeners. French, climbing and bush beans rarely cross-pollinate, and so are very simple plants from which to save seeds. Leave some pods on the plants until the pods are completely dry, shell the beans and leave them to air dry. These can be used as seeds the following season. F1 (Filial 1) hybrid varieties are not suitable for saving seeds. F1 hybrids are a cross between two pure-bred varieties, selected for disease resistance and cold tolerance, as well as size and fruit yield. Saved seeds from F1 hybrids are second-generation hybrids, which are not stable, meaning you may get reduced or no fruit production, stunted growth or no germination.
Mice will readily dig up bean seeds if given the opportunity. If possible, bean seeds should be covered with netting until they germinate, but it can be difficult to ensure the netting is rodent proof, as a mouse can squeeze through a very small hole. Mice will not cross sulfur, so ash from organic materials (weeds and wood) can be sprinkled liberally over the area where the bean seeds are planted, as ash contains sulfur. This process not only deters mice, but helps to fertilize the plants, as ash is a valuable fertilizer. Rabbits and deer pose a danger to young bean plants, as these animals will strip the leaves and eat the growing tips.
All types of beans, except some broad bean varieties, are very susceptible to damage from frost and cold temperatures. Bean plants should not be planted outside until the danger of frost has passed. Even a mild frost can cause serious damage to bean plants of any size, killing the plant or stunting growth. For an early crop of beans, the seeds can be planted in trays indoors or in a greenhouse, and transplanted outside when the risk of frost has ended. Some broad bean varieties, such as Aquadulce, may be over-wintered (planted in the ground in late winter) for an extra early crop the following season.