Runner beans are a delicious veg plot staple – they’re one of the easiest crops to grow and produce an abundance of long green pods over several months. Most varieties are climbers, grown up tall canes, producing large harvests in a small area. A few dwarf varieties are also available, ideal for large containers. Pick when young, for tasty stringless beans.
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Runner beans are tender plants that won’t survive frost, so for an early crop sow indoors in late spring. You can also sow outdoors in early summer. Alternatively, young plants can be bought from garden centres and online suppliers in spring, ready for planting outside.
Most runner beans are climbers – they need tall, sturdy supports and do best in the ground, but can also be grown in large containers. As they grow vertically, climbers produce a large crop in a small area of ground. There are also some dwarf varieties – these are quick to grow, but produce a smaller crop. They are useful for raised beds and containers, and for gardens in exposed sites. Climbing beans take longer to reach cropping stage, but produce beans over a longer period, from mid-summer to early autumn if picked regularly.
Runner beans are attractive as well as productive, with red, white or bi-coloured flowers, depending on the variety.
You’ll find a huge range of varieties available as seed in garden centres and online. Look in particular for varieties with an RHS Award of Garden Merit (AGM), which shows they performed well in trials – see our list of AGM fruit and veg.
If you have space, start runner beans off indoors – on a sunny windowsill, in a propagator or in a greenhouse – from mid-April to May. This will give you an earlier crop. Choose pots 7–8cm (2.5–3in) wide and fill with moist multi-purpose compost. Sow one bean into the centre, 5cm (2in) deep, and water well.
Keep in a warm, bright place, at over 12°C (54°F). Seedlings will grow rapidly and need watering regularly.
The young plants can be transplanted outside once all risk of frost has passed, usually in late May/early June – see Plant outside, below.
Sow outdoors – in containers
You can sow seeds outdoors into pots of multi-purpose compost in spring – either into small pots for transplanting into the ground later, or into large containers as their final growing site.
Sow one bean per small pot, 5cm (2in) deep, and place in a coldframe or sheltered position. Once the plants reach 8cm (3in) tall, in June or July, plant them into their final positions – see Plant outside, below.
Alternatively, sow into large containers, positioned in a sheltered, sunny spot, as their final growing site. For dwarf beans the container should be 30–45cm (12–18in) wide, and for climbing beans 75cm (30in) wide and 45cm (18in) deep – a large tub or half-barrel is ideal.
Simply sow the seeds direct into the container, spacing them 15cm (6in) apart. Insert a wigwam of 1.8m (6ft) canes to support climbing varieties (see Grow below), and choose a heavy container to keep it from toppling over. Dwarf beans don’t usually need support and look great cascading over the sides.
Sow outdoors – in the ground
Runner beans thrive in rich, deep, fertile soil in full sun. If possible, it’s best to improve the soil with organic matter the autumn before sowing. Alternatively, it can be done a couple of weeks beforehand, to give time for the ground to settle. A pH of 6.5 (slightly acid) is preferable – add lime if your soil is more acidic.
Seeds need warm conditions to germinate, so wait until all risk of frost has passed and your soil has reached 12°C (54°F) – usually by mid-May in the south of the UK, and two weeks later in the north. If your soil is heavy and wet, it can be pre-warmed in early spring by covering it with clear plastic or cloches for about four weeks before sowing.
It’s also best to put the supports in place first – usually tall bamboo canes in a wigwam or double row (see Grow below).
Sow the large seeds individually 5cm (2in) deep – two at the base of each cane, which should be spaced 15cm (6in) apart. Thin to one seedling per cane, and protect plants from slugs and snails.
When sowing dwarf runner beans in the ground, allow 30cm (1ft) between plants and 50cm (20in) between rows.
If you sow one batch early (indoors in April/May), you can also sow a later batch outdoors in July, to prolong your harvests, allowing you to gather beans until the first frosts.
Wait until after the last frost before planting indoor-raised or bought young plants outside. Then harden them off to acclimatise them to outdoor conditions for a couple of weeks, either by putting them in a coldframe or placing them in a warm, sheltered spot, covered with fleece.
If planting in the ground, enrich the soil with well-rotted manure or garden compost – ideally at least two weeks before planting, to give the ground time to settle. Even better, do it the autumn before planting. When growing in rows, the traditional method for preparing the soil is to dig a bean trench:
Mark out a line, then dig a trench 90cm (3ft) wide and 60cm (2ft) deep. Loosen the soil in the base by forking it over
Scatter well-rotted manure or home-made garden compost in the base of the trench and mix with the soil from the trench. Return the improved soil to the trench
Add pelleted poultry manure at the manufacturer’s recommended rate
With climbing beans, it’s also best to put the supports in place before planting – see Grow, below.
Once your bean plants are hardened off, plant them into their final growing position, in the ground or in a large container, in a sunny, sheltered spot. Water the plants well, both before and after planting.
Plant one climbing bean plant at the base of each cane, and loosely tie their stems to the canes to get them started. When planting dwarf beans, space them 30cm (1ft) apart.
If planting in a container, choose multi-purpose or loam-based compost. Containers should be at least 30–45cm (12–18in) wide for dwarf beans, and 75cm (30in) wide and 45cm (18in) deep for climbing beans.
Supporting runner beans
Runner beans need tall, sturdy supports to climb up. The traditional method is to grow them up a double row of bamboo canes (1.8m/6ft tall), with 45–60cm (18in–2ft) between the two rows. Space the canes 15cm (6in) apart within each row and slope them inwards, then tie near the top to a horizontal cane, to form a sturdy A-frame. If growing more than one double row, allow 1.5m (5ft) between them.
Alternatively, create an X-frame by sloping the canes at a sharper angle so they cross in the middle. Tie them at the centre, and add a horizontal cane to link them all together and increase stability. An X-frame takes up more space, but picking is easier and cropping is usually better.
If you don’t have room for a double row of canes, you can make wigwams. Again, use 1.8m (6ft) canes, four or five per wigwam, spacing them 15cm (6in) apart at the base. Tie the tops of the canes together – or use cane support rings or ceramic finials to hold the canes together. Wigwams make an attractive feature in a border or veg plot and also work well when growing in containers.
Loosely tie young plants to the canes to get them started – after that they will climb naturally. Remove the growing point once the plants reach the top of their support. This encourages side-shoots and prevents plants becoming top-heavy.
Another support option is to use 10cm (4in) polyethylene pea/bean netting, secured to tall posts or placed over a frame.
Dwarf beans don’t usually need support, although you can insert short twiggy sticks between them to keep them upright and lift the beans off the ground.
Watering and mulching
Runner beans are thirsty plants and crop best when watered regularly, especially once they start to flower and form pods. You will typically need to apply 5–9 litres (1–2 gallons) of water per square metre/yard every three to four days. Regular and generous watering is particularly important for plants growing in containers, which dry out more quickly.
Spread a thick mulch of well-rotted manure or mushroom compost over the soil in July to help hold in moisture.
Encouraging pods to form
Runner bean flowers sometimes fail to ‘set’ (produce pods) – there are several possible causes and solutions:
Ensure the soil is constantly moist and doesn’t dry out. Add mulch after planting and water regularly and generously, ideally in the evenings.
Flower set is better in alkaline, chalky soil. If your soil is neutral or acidic, try applying lime.
If this is a recurring problem and you live in a mild area, try growing varieties with some French bean parentage, which set pods more easily in warmer summers. Examples include ‘Firestorm’ and ‘Moonlight’.
Pick pods when young and tender, about 15–20cm (6–8in) long. The pods should snap easily and the beans inside should still be small and pale in colour.
Regular harvesting – ideally every two to three days – is essential to prevent any pods reaching maturity. Once this happens, plants will stop flowering and no more pods will form.
Occasionally, fungal or bacterial diseases such as rust or halo blight can develop, while in warm, dry conditions red spider mites may get established.
The southern green shield bug is a relatively new pest found on runner beans and – although only in certain locations at present – is more serious than our native shield bugs, which do negligible harm to runner beans.
Black bean aphid
Sap-sucking aphids will disfigure plants and cause stunting to leaves and stems.
In the case of broad beans, pinch out infested tips. On other beans, catch populations when small and squash.
Slugs and snails
These feed on the young seedlings and you'll see the tell tale slime trail on the soil around your crop, as well as on the leaves.
There are many ways to control slugs and snails, including beer traps, sawdust or eggshell barriers, copper tape and biocontrols.
No/ very few beans
This is one of the most common problems of bean growing and is usually caused by lack of moisture and/or poor pollination by insects.
Plant or sow beans into soil that has had plenty of organic matter, such as well-rotted manure added the previous autumn, as this will aid moisture and nutrient retention around the roots. Plant in a sheltered site as this will encourage bees to visit and pollinate the plants.
A common fungal disease of many plants that can be recognised by orange, yellow or black spots or blisters that form on leaves, along with pale and distorted stems. Leaves can fall and in severe cases, plants will eventually die.
Dig up badly infected plants and dispose of to prevent the spores spreading to other plants. Carefully check plants before buying to ensure they are healthy and show no signs of disease.
Nigel Slater recommends serving runner beans with lemon and garlic crumbs, as a lovely side dish for grilled fish.
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