Runner bean seeds are large and easy to sow. They need warm conditions to germinate.
Sowing indoors in April and early May:
- Fill pots (7-8cm/2.5 -3 in) with moist multipurpose compost
- Sow one seed per pot, 5cm (2in) deep. Water well
- Grow in warm conditions of over 12°C (54°F). A greenhouse or sunny windowsill is ideal
- Harden off the young bean plants gradually and plant out when the risk of frost has passed
Soil preparation: In the autumn before sowing, improve the soil with organic matter. A pH of 6.5 (slightly acid) is preferable; add lime if the soil is more acidic.
In early spring, if your soil is heavy and wet, it can be pre-warmed by covering it with clear plastic or cloches for about four weeks before sowing.
Making a bean trench: Runner beans thrive in a rich deep, fertile soil in full sun. A bean trench is a traditional way of preparing the soil, especially if your soil is poor, but is not essential as the usual digging methods are just as good.
- Mark out a line and dig out a trench 90cm (3ft) wide and 60cm (2ft) deep. Loosen the soil at the base by forking it over
- Scatter well-rotted manure or home-made compost in the bottom of the trench and mix with the soil from the trench. Return the improved soil to the trench. Add pelleted poultry manure at the manufacturers’ recommended rate
- Leave the soil to settle for at least two weeks before planting
Making a support: Before sowing, construct a support system for your beans, as they are strong climbers. There are a number of ways in which you can train runner beans:
- Many gardeners use a double row of inwardly sloping 2.4m (8ft) tall bamboo canes or hazel poles tied near their top to form a long A-frame. These are secured to a horizontal cane across the top. This method can be modified by tying the canes at a lower point to form more of an X-shape. This usually makes for easier picking and better yield
- Using 10cm (4in) polyethylene pea/bean netting supported by tall posts or placed over a frame is an alternative support
- Wigwams formed of three or more bamboo canes are the least work to construct, make good use of space in small gardens and add interest to mixed borders. Specially-designed wigwam cane support rings or ceramic finials are available to make it even easier
Plant out pot-raised beans in late May and early June, one plant per cane. Alternatively, sow your chosen runner beans from mid-May until July, 5cm (2in) deep, two seeds to a 2.4m (8ft) bamboo cane, spaced 15cm (6in) apart; thin to one seedling per cane. When planting double rows, space the two lines of beans 60cm (2ft) apart, allowing 1.5m (5ft) between rows.
Sow bush cultivars 5cm (2in) deep, 30cm (1ft) between plants and 50cm (20in) between rows.
Care of runner beans
- When shoots have reached the top of their supports, pinch them out to prevent plants from becoming top-heavy
- Runner beans need copious amounts of water, especially if the weather is dry when the buds start to appear. Throughout the season, apply 5-9 litres water per sq m (1-2 gallons per sq yd) every three-to-four days
Beans are ready when the pods are less than full length, snap easily and while the seeds are still small and pale in colour. This is usually at about 15-20cm (6-8in) long.
Pick the beans regularly to encourage further pod production; every two or three days is ideal. If beans are allowed to go to seed on the plant, they will stop producing flowers and beans.