Runner beans

Suitable for...

There is a wide range of runner bean cultivars available both climbing and bush (dwarf).

When to sow runner beans

Sow runner beans under cover from the beginning of May and plant out in June. This is a good idea if you are keen to harvest early crops, you are gardening in northern areas or you garden on heavy soils.

When the soil has reached 12°C (54°F), seeds can be sown in their permanent positions every two weeks, if needed, until the end of July. In this way you can harvest beans until the first frosts.

How to grow runner beans

Seed sowing

Runner bean seeds are large and easy to sow. They need warm conditions to germinate.

Sowing indoors in April and early May:

1. Fill deep pots (15cm/6in) with multipurpose compost and water well
2. Sow one seed per pot, 5cm (2in) deep
3. Grow in warm conditions of over 12°C (54°F). A greenhouse or sunny windowsill is ideal
4. Harden off the young bean plants gradually and plant out when the risk of frost has passed

Sowing outdoors

Soil preparation: 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 usual digging methods are just as good.

1. 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
2. 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
3. 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

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 plant per cane.

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

Harvesting

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.

Cultivar Selection

Climbing runner beans

Traditional cultivars have a climbing habit and require tall supports. They are heavy-cropping. For recommended cultivars please see the results of our runner bean trials.

Dwarf runner beans

Non-climbing bush or dwarf runner beans produce respectable crops of rather lower-quality beans than the climbers. They are useful for raised beds and container gardening or gardens in exposed positions.

Bi-coloured flowering cultivars

For bi-coloured flowers, try ‘St George’ AGM (climber), ‘Hestia’ (dwarf) or ‘Painted Lady’ (climber).

Problems

Runner beans are one of the easiest vegetables to grow. However, they can get a number of problems;

Sometimes pods do not set. Usually this is due to lack of water, but there are other causes.

Occasionally, runner beans are affected by fungal diseases such as haloblight and runner bean and French bean rust.

One of the more common pests of bean is the black bean aphid. Red spider mite can also occur especially in warm, dry conditions. The southern green shield bug is a relatively new pest found on runner beans.