Robin Gale-Baker, from Sustainable Macleod, discusses growing broad beans. She has also written articles for this website about growing cauliflower, eggplants and capsicums, other vegetables, apricot trees, persimmon trees, other fruit trees, herbs and growing techniques.
Broad beans are a wonderful crop to grow for four reasons: they are a delicious and nutritious food; they add nitrogen to the soil; they supply great colour; and they attract bees to aid pollination in the garden.
Broad beans can be sown from Autumn to Spring. Winter is a good time to plant them. They are frost tolerant. Whilst Autumn-sown plants are ready for harvest in 25 weeks, spring-sown are ready in 15 weeks.
Broad beans require an open, sunny position, and shelter from wind if possible. They thrive in neutral soil. To prepare your beds, fork over your soil to aerate it and dig in a low nitrogen, well-rotted animal manure such as cow, sheep or horse plus compost to provide organic content, nutrients and good drainage. Sprinkle potash at the rate of 1 tablespoon per square metre to strengthen plant stems and encourage flowering.
Plant spacing depends on the variety and height but is generally 20-30 cm apart (follow the directions on the packet). Double rows close together can be sown so that the rows support each other. Crimson Flowered and Chocolate Flowered grow to 90 cm, Coles Early Dwarf, Scarlet Cambridge and Aquadulce to 1m and Early Long Pod to 1.5m. The tall ones are divided into long and short pod varieties. Planting depth is recommended between 2-10 cm. I always plant at least 5cm deep to avoid rats eating the seed. Soak your seed in either water or a weak seaweed solution overnight and, once planted, water the seed in and don’t water again until the shoots emerge above ground. Once the flowers have opened, water well so that the pods develop properly. Constant picking of pods causes plentiful new growth.
Broad beans don’t suffer many pests but snails can be a problem and you may see them at night on the leaves. Black tip and spot is a fungal problem that is caused by poor drainage and black fly can infest tender top shoots, which can be remedied by picking out the tips.
There are various ways of supporting broad beans so that their brittle stems aren’t at risk of snapping in the wind. They can be individually staked with bamboo but that is a lot of work; they can be supported by 4 corner stakes surrounded by a cordon of heavy string which can be further criss-crossed in a lattice pattern; you can use last season’s corn patch and leave the stripped stalks in place as a support structure and also add a string lattice; or you can use your tomato cages from summer which is a handy way of storing them.
Broad beans convert nitrogen from the air into nitrogen root nodules so, when the crop has finished, slash it and dig in the stalks and roots to add valuable nitrogen to your soil. You can also cut the stalks at their base and leave the roots intact in the soil and dig the shredded stalks into another bed.
Save seed from your crop for next year. The easiest way is to leave pods on the plants until they dry out, then shuck the pods and store the beans in an air tight container.
Good companion plants include sweetcorn, potatoes and lettuce. Avoid fennel.
Broad beans are delicious when young and small but tough when they are older and bigger (which sometimes gives them an undeserved, poor reputation). Young broad beans can be steamed, or eaten pods and all. The tips can be stir fried and the flowers can be eaten in salads. Tough older beans can be steamed and double shelled, removing the tough grey outer skin. Mashed broad beans with lemon, dill and creme fraiche make a delicious dip.