Do you want to save your own bean seeds for growing next year? Do you want to re-grow the same fabulous beans next year that you grew this year? It may not be as easy to do with any other plant than the “bean bunch”… ya know why?
Beans are self-pollinating and rarely pollinated by insects. Bean flowers release pollen the night before the flowers open. The next day, as the flowers open, the anthers brush against the stigma and pollination occurs. So, even if you see insects on your open bean flowers, you can be fairly sure that pollination happened before the visitors arrived. For this reason, it is possible to grow bean varieties close together with little worry of cross-pollination if you are planning to save some of the resulting seeds. Bush beans can be grown closer together than pole beans, which should have at least 2 feet of separation. Runner beans and Lima beans are pollinated by bees and are more likely to cross-pollinate than other varieties, so would require more distance apart.