This Allotment Pro editorial draft summarises the cited RHS guide. Check the source and adjust timings for local conditions.RHS source guide
In mild regions or a warm, sheltered, freely drained site, sow a hardy cultivar for an early crop and protect young plants during cold spells
Start individual seeds under cover, or sow hardy cultivars outside in mild, sheltered districts
Sow successive batches, principally in March and April and into early May, to spread the summer harvest
Harden off indoor-raised or bought young plants, then set them into prepared ground in early to mid-spring
Harvest from late spring to late summer according to sowing date and cultivar, checking the lowest pods every few days
Broad beans are straightforward, productive vegetables that can provide one of the earliest bean harvests of the year. Sowing at several points from autumn to late spring lets suitable gardens extend picking from late spring through summer.
Choose a sunny, sheltered site with rich, free-draining soil. Plants need relatively little routine attention, although flowers benefit from water in dry weather and developing pods should be picked frequently. Dwarf cultivars suit containers, small plots and exposed sites, while taller forms usually need support.
Cultivars differ in sowing season, plant height, pod length, bean colour and harvest timing. Hardy types can overwinter from autumn sowing in suitable conditions; others are intended for late-winter or spring sowing. Dwarf plants reach about 50cm (20in), making them convenient where space is limited or wind is a concern.
Seed is widely available from garden centres and online suppliers. Young plants are another option in spring for growers without space or time to raise their own seedlings.
A leading choice for autumn sowing and overwintering, producing long pods that mature early.
A heritage broad bean with slender pods up to 20cm (8in) long, typically holding seven or eight beans.
A fast-growing spring-sown cultivar reaching up to 1m (3ft 3in), with an early crop of long pods.
An early dwarf cultivar only about 45cm (18in) tall, useful for containers and windy gardens.
Select a warm, sunny and sheltered bed with good drainage. Remove weeds thoroughly, then improve the soil’s moisture-holding capacity with at least two bucketfuls of well-rotted manure or homemade garden compost per square metre or square yard. Ideally prepare the bed several weeks before sowing or planting so it can settle.
For a no-dig approach, spread organic matter over the surface and sow or plant through the mulch instead of forking it into the soil.
Broad beans are usually sown under cover from late winter or directly outdoors in spring. Autumn sowing is reserved for hardy cultivars in mild regions or especially warm, sheltered and freely drained positions.
From February, sow each large seed separately in a small pot or module filled with peat-free multipurpose compost. Insert it 5cm (2in) deep with the scar facing downwards, water well and keep the seedlings in a bright place. This protected start is particularly useful where wet soil might rot seed, or where mice, slugs and snails threaten outdoor sowings.
Sow the main crop in March and April, continuing into early May if required. In mild, sheltered districts, hardy cultivars can also be sown in October or November, or in February. Cover early young plants with cloches or plastic-free fleece during cold spells.
In open ground, place seed scar-side down, 5–7.5cm (2–3in) deep and 15–23cm (6–9in) apart according to cultivar. Space single rows 45cm (18in) apart. For double rows, leave 23cm (9in) between the paired rows and 60cm (2ft) between each pair. Sow spare seeds at the row end to replace failures, and make further batches a few weeks apart for a longer harvest.
Use a dwarf cultivar and a large container at least 40cm (15in) wide, filled with peat-free multipurpose or loam-based compost. Sow scar-side down, 5cm (2in) deep and 15cm (6in) apart.
Harden off seedlings raised indoors, or bought plug plants, before moving them outside in early to mid-spring. Plant into prepared ground 15–23cm (6–9in) apart. Use either single rows 45cm (18in) apart or double rows 23cm (9in) apart with 60cm (2ft) between each pair, then water thoroughly.
Dwarf plants can also be set 15cm (6in) apart in a container at least 40cm (15in) wide. Fill it with peat-free multipurpose or loam-based compost and place it in a sunny, sheltered position.
Broad beans in fertile ground are generally undemanding. Priorities are timely watering as flowering starts, moisture conservation, weed control, support for taller plants and removal of aphid-prone shoot tips once pods begin to form.
Ground-grown plants usually need extra water only on light, free-draining soil or during dry spells. A thorough soak at the start of flowering and another two weeks later can substantially improve the crop. Containers dry faster and need frequent watering throughout active growth.
After planting, apply a deep layer of garden compost around the plants to hold soil moisture and suppress germinating weeds. Broad beans in ordinary garden soil rarely require extra feed. For dwarf plants in containers, begin a high-potassium liquid fertiliser when the first flowers open and repeat once every two weeks, following the product directions.
Hoe regularly between rows, especially while the crop is young, to reduce competition for water and light.
Most tall cultivars benefit from staking. Put a sturdy stake at each row corner and at 1.2m (4ft) intervals along the sides, then run string around them in tiers 30cm (1ft) apart from ground level. Dwarf plants in double rows often support one another, although twiggy sticks can be added if necessary.
When the lowest flowers have formed small pods, remove the soft growing tip from each plant. This redirects energy towards the pods and removes the tender growth most attractive to black bean aphids. The tips can be steamed or stir-fried.
Harvest time runs from late spring to late summer, depending on cultivar and sowing date. For shelled beans, pick pods when they are full but still fairly small; the beans are sweeter and more tender before the attachment scar changes from white or green to black.
Very young pods can be picked at about 7cm (3in) long and cooked whole. Cut pods with secateurs or scissors rather than pulling, starting with the lowest ones and checking every few days. Frequent picking encourages further pods, and young shoot tips can also be harvested like spinach.
After the final harvest, cut the stems to ground level and compost them. Leave the nitrogen-fixing roots in place to contribute to soil fertility, or dig the whole plants into the soil.
Outdoor seed may be taken by mice and voles, while slugs and snails can damage young growth. Later in the season, blackfly commonly gathers on tender tips. Good spacing, regular inspection and prompt harvesting also make it easier to detect fungal diseases and seed pests.
This fungal disease produces dark chocolate-coloured lesions on leaves, stems, flowers and pods. It is most damaging in cool, damp, crowded conditions, when spots can expand and plants may lose flowers or collapse.
Problem sourceLook for small, dusty dark-brown spots with pale yellow margins on leaves and stems. The fungal infection is common on broad beans and can reduce healthy leaf area.
Problem sourceDense colonies of black aphids gather on soft shoot tips during spring and summer. Pinching out the tips after the lowest pods form removes their preferred feeding site.
Problem sourceThis beetle is most often noticed in dried broad beans, particularly by gardeners saving their own seed. Check stored seed before keeping it for sowing.
Problem sourceSmall rodents can remove broad bean seed from outdoor sowings. Starting seed in individual pots or modules under cover avoids this vulnerable stage in the ground.
Problem sourceAdult weevils make distinctive semicircular notches along leaf margins in spring. The damage can look severe but often has little effect on an established crop.
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