How to grow broad beans and the best varieties

Broad beans are a traditional allotment crop that, sown in November, can provide one of the first fresh pickings of summer. You can also sow in spring. 

The Which? Gardening magazine experts have trialled varieties to help you find the best ones to grow for big crops of tasty beans.

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How to grow broad beans: month by month

Best broad bean varieties

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How to grow 

Sowing

Some varieties are hardy and can be sown in October or November. Our trial (Nov 02) showed that this generally brings the harvest forward by three weeks. Either sow the seeds in module trays using a Best Buy compost for sowing seeds and then plant out, or sow direct in double rows 20cm apart each way in a fertile, well-prepared seed bed. Covering with fleece helps to keep out the worst of the cold.

Alternatively, delay sowing until spring. You can sow under cover in February-March into large modules for planting out as strong seedlings once the soil is workable. 

Planting

The seeds should germinate in 7-10 days and indoor sowings will be ready to plant out a month after sowing. Be sure to harden them off beforehand. Work a balanced fertiliser, such as Growmore or pelleted chicken manure, into the soil. 

Caring for your plants

Give plants a good soaking once a week in dry spells, especially when flowers and pods are forming. Support taller varieties with lengths of string along the rows supported by stakes.

Harvesting

Pick the lower pods first in early to mid-July.

Problems

Chocolate spot

Chocolate spot causes reddish-brown blotching of broad-bean leaves, stems and pods. It can spread rapidly, becoming brown-black, joining up and covering leaves. In addition, the leaves are covered with a grey mould in wet weather. The flowers and young pods are quickly ruined, and the disease will penetrate older pods to discolour the seeds inside. 

Chocolate spot may appear from mid-winter onwards. Wet weather is needed for the disease to spread. Autumn-sown broad beans are most likely to be infected, but even in spring the disease can be troublesome. 

Broad beans grown in fertile, well-drained soils resist attacks. So make sure your soil has plenty of phosphate and potash. If your soil lacks these nutrients, add 30g a sq m each of superphosphate and sulphate of potash to the bean plot in winter. To improve the drainage in your plot, consider making raised beds for vegetable growing. In wet or cold districts, raising overwintered broad beans under cloches may help to prevent disease. It's also a good idea to plant autumn-sown beans at wide spacings, so airflow through the plants is enough to keep the humidity down. When you sow, leave 50cm between the rows and 10cm between plants.

Rust

Broad beans are often attacked by a rust which covers the leaves with tiny yellow spots. Red-brown powdery spots develop later on the underside of leaves, and stems and pods can be affected.

Usually it develops too late to affect the yield of beans. However, late-sown spring beans can suffer badly in July, when the warm days and dewy nights favour the disease. There are no chemical controls available to gardeners.

Picking off and destroying infected leaves may slow the disease down. Tiny mites often feed on the spores in the pustules – these mites are harmless.

Blackfly

Blackfly are very common on broad beans, clustering around the growing tips from May onwards. Pinch these out once five flower trusses have developed, or squash aphids between gloved fingers and thumb.

Read more about blackfly

Pea and bean weevil

The adults of this pest make characteristic U-shaped notching all round the leaf edges in spring. Although they do spread viral diseases, they do not usually do significant damage in the garden unless very young plants are attacked. Usually, however, the plants will grow out of the vulnerable stage with little loss of crop. The larvae feed on the roots of the plant and are only noticeable when the crop is pulled up. They are small (up to 5mm long) white grubs with no legs and brown heads, that look very like vine-weevil grubs. They can sometimes be seen feeding on the nitrogen-fixing nodules.

To avoid attack, prepare the soil well, making a fine tilth. If the soil is poor, boost the seedlings' growth before sowing by adding extra fertiliser, such as growmore (rake in 70g a sq m). Water the young plants if necessary to keep them growing steadily and cover them with garden fleece in cold weather. Covering before the seedlings emerge will exclude not only pea and bean weevil, but also blackfly and birds too. Keeping the rows well hoed will also reduce the chances of damage. There is no realistic physical way of controlling the root-eating larvae. There are no chemical controls available for adults or larvae. An alternative is to start broad beans off in pots to plant out when large enough to avoid serious damage.

How we test broad beans

We sowed our broad bean seeds in modules in the greenhouse in March and planted out our seedlings in early May. We harvested beans weekly during July and August, weighing and counting the whole pods and the shelled beans, then assessed the quality of the shelled beans and tasted all the varieties raw and lightly steamed. We also recorded any pests or diseases that affected the plants.