May is the ideal time to sow tender beans. Unlike hardy broad beans, they require warmth and will not survive frost. Earlier crops can be achieved by sowing in April indoors.
Runner beans are by far the most popular tender bean in Britain. Tuberous-rooted perennials grown as annuals, they come from Central America and do best with warm days and mild nights.
For early crops, in northern areas and on heavy soils, they are best raised in pots of multipurpose compost and planted out in June. Alternatively, sow outdoors from mid-May until July, 5cm (2in) deep, two seeds to a 2.4m (8ft) bamboo cane, spaced 15cm (6in) apart; thin to one plant per cane. Most people grow climbing beans up rows of canes and string, but wigwams are probably less work, better for small gardens or adding interest to mixed borders.
Non-climbing bush or dwarf runner beans produce respectable crops of rather lower-quality beans than the climbers. Sow bush cultivars 5cm (2in) deep, 30cm (12in) between plants and 50cm (20in) between rows.
Runner beans need careful watering in dry spells to set pods, and hot nights can reduce pod set. French beans are a more robust alternative in hot, dry districts, but should be sown in batches every couple of weeks as they do not crop for as long as runners. Lablab and yard-long beans are tender beans from the tropics, and are grown in the same way; they are ornamental, but disappoint in cold, wet summers. Lablab are widely eaten in the tropics, but are perhaps best treated as ornamentals in the UK as uncertainty persists over the presence of toxins in the seeds and pods.
Top beans
Beans yield protein-rich pods and seeds, and can be highly ornamental.
Runner bean (Phaseolus coccineus): Flat-podded, tender perennials grown as annuals. They are native to Central America, but crop well in mild, moist weather. Climbing kinds need support and can reach 2m (6.5ft) high.
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French bean (P. vulgaris): Easy annuals with flat or rounded pods on quick-growing vines up to 2m (6.5ft) high. Dwarf cultivars are bushy, heavy cropping and grow to 50cm (20in). They originate from South America.
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Broad bean (Vicia faba): Hardy, easy-to-grow annuals 40-150cm (16in-5ft) tall. The immature seeds are eaten fresh, but young pods and tips are tasty too. The mature seeds feature strongly in Middle Eastern cooking.
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To save your own seed
Runner beans cross-pollinate and seedlings may not be true to type if other runners are growing nearby. French beans self-pollinate and seeds usually come true. In both cases, allow selected pods to mature on the plants until papery, then pick and leave to dry indoors. When they are crisp, shell and store the beans in a cool, dry and dark place for the following year.