Also known as kidney, snap or string beans, they are tender annuals with climbing, dwarf or intermediate forms that bear round, flat or curved pods of 7-20 cm long. They may be green, yellow, purple, red or green flecked with purple.
They need optimum growing temperatures of 16-30 Celsius degrees (61-86 F) and will not tolerate temperatures below 10 Celsius degrees (50 F). They are self-pollinated, need a rich, light soil with good drainage to prevent root rot. For best results work plenty of well-rotted compost or manure into the soil before planting and always rotate crops.
In cool climates you can grow dwarf French beans to maturity under cloches, in a greenhouse or polytunnel. Space plants as in the open at 15 cm apart.
Seeds of French beans may be pre-germinated before sowing by spreading the beans out on moist tissue paper in a tray without drainage holes, keeping them damp at minimum 12 Celsius degrees (54 F). when the shoots begin to appear and before they turn green, pot them up carefully or sow them directly in their final position outside at 4 cm deep. Place the climbing forms at 15 cm apart and 60 cm between rows and dwarf forms at 22 cm equidistant spacing.
Support climbing forms using crosses cane rows, wigwams or netting supports. Mulch and never allow the plants to dry out completely by watering them in dry conditions at flowering time at a rate of 22 litres per sqm.
Harvest French beans after 7-13 weeks. If you want to use them fresh or for freezing pick young beans regularly. In damp climates pull up plants and hang them by the roots in a dry, frost-free place and once they are dried, remove the pods and extract the beans and store them in an airtight jar.
