How to Grow Broad Beans in Australia

Broad bean (Vicia faba), also called fava bean, is a cool-season legume in the pea family, Fabaceae, grown for plump beans and young pods. Unlike the warm-season French and runner beans in How to Grow Beans, broad beans go in as autumn cools. A common failure is sowing too early, which gives tall plants that set few pods.

Three mistakes that matter

1. Sowing too early. Seed sown into warm late-summer soil grows tall and leafy, and the top flowers may not set until spring. Sow inside your zone's months in When to plant, so plants flower in mild weather.
2. Feeding for leaves. The roots make much of their own nitrogen, so rich manure or a high-nitrogen feed gives soft, top-heavy plants with few pods. That sappy growth also blows over, catches fungal disease and feeds aphids.
3. Leaving tall plants unstaked. One gusty spell can snap a block of brittle stems just as the pods fill. Put stakes and string around tall lines early, as Care by growth stage describes, or grow 'Coles Dwarf' in exposed beds.

When to plant

Broad bean seed germinates in soil from 6°C to 24°C, so sow as autumn cools rather than in late-summer heat. Aim for flowering in late winter and spring, when lengthening days and air near 20°C let pods set. Sow two or three batches about three weeks apart to spread the picking.

Across the south, Anzac Day falls in the heart of the window. Late sowings run into hot late-spring days that cut the crop short, so finish by the last month listed for your zone.

Site, soil and setup

Full sun and shelter from strong wind suit broad beans best, since wind lowers the crop and flattens tall plants. They cope with heavier soil and brief waterlogging better than most vegetables, though free-draining soil is still the ideal.

Chocolate spot survives in the soil for several years, and rust lives on in old bean stems and self-sown plants. That is why the bed moves each year.

Container growing

The short 'Coles Dwarf' is the line for pots. Give it a pot at least 40 cm across, which holds about 28 L, filled with premium potting mix. Taller lines need a frame and room to lean, so they belong in the ground.

• Water: when the surface of the mix feels dry, and never let it dry out once flowers open.
• Feed: liquid potash at the rate on the label, fortnightly from the first flowers.
• Position: full sun out of the wind, with a short stake or two to steady the plants.

Sowing Seeds

Sow broad beans straight into the bed: the big seed handles easily, and seedlings dislike being moved.

Choosing a line

Sowing direct

• Push seed 30 to 50 mm deep, at the spacing in Site, soil and setup.
• Water well once at sowing, then hold off until shoots show, because cold, wet soil rots the seed.
• Seedlings usually emerge in 8 to 14 days, slower in cold soil.
• Sow a few spare seeds at the end of the row to fill any gaps.
• Where mice dig up seed or the soil stays sodden, start seed in small pots and plant out while young.

Care by growth stage

Steady moisture and mild weather at flowering decide the crop. Feed lightly, because the root nodules supply much of the nitrogen.

Tall lines need support while they are still short. Drive a stake at each corner of the block and run string around the outside at two or three heights as the plants grow. If growth stalls in poor soil, a light dose of all-purpose controlled release granular (NPK around 14-5-10) scratched into the soil can help.

Pinching Out Tips

Once the lowest flowers have set small pods, pinch the soft top out of each tall stem. The plant then puts its effort into pods, and the tender tips aphids crowd onto are gone.

• Nip off the top few centimetres of each stem with finger and thumb.
• Steam clean tips as a leafy green.
• Drop tips already crusted with aphids into a bag for the bin.
• In warmer areas, pinch dwarf plants as well, to help pods set.

Companion planting

Good partners use the nitrogen broad beans leave behind or share their bed and stakes; the plants to keep apart harbour their diseases and pests.

Grows well with

• Kale and lettuce, hungry leaf crops that draw on the nitrogen the bean roots add.
• Peas, which like the same limed bed and can climb the same stakes.

Keep apart

• Vetch and lentils, hosts of the chocolate spot fungi.
• Capeweed, which harbours redlegged earth mite.

Harvesting Pods

Pods ripen from the base of the stem upwards, so check the lowest ones first as they begin to swell.

• For eating whole, pick pods small and young, before the beans fill out.
• For shelled beans, pick pods longer than 15 cm, with beans about the size of a five-cent coin.
• Pick before the tissue joining each bean to the pod turns black and the skins toughen.
• Pick often, since regular picking keeps new pods coming.
• Harvest in the cool of the morning and keep the pods cool.

Fresh broad beans keep only briefly, so refrigerate the pods and use them soon. For longer keeping, shell the beans, blanch them and freeze.

Steam or boil the beans, and slip older ones out of their tough outer skins after cooking. Beans of 'Coles Dwarf' and 'Egyptian (Fava)' can also be dried for soups and stews.

Common problems

Flowers but no pods. Frost damages open flowers, and heat or dry spells stall pod set; keep water steady at flowering and sow on time.

Tall, leafy plants with few pods. Too much nitrogen or too early a start; see Three mistakes that matter.

Gaps in the row. Seed rotted in cold, wet soil or mice took it; resow the spares and water less until shoots appear.

Tough, floury beans. The pods stayed on too long; pick at the signs in Harvesting Pods.

Silvery patches on seedling leaves. Redlegged earth mite feeding, often mistaken for frost or chocolate spot; see Pests and diseases.

Pests and diseases

Most trouble arrives in spring, when warm, humid days meet a dense block of flowers and pods.

Cowpea aphid (Aphis craccivora). Black or dark grey aphids that crowd densely onto legume stems and soft tips. Faba bean aphid (Megoura crassicauda), dark green with a black head, also turns up in New South Wales and Victoria. Pinch out infested tips, hose off small colonies or spray insecticidal soap. Read more

Native budworm (Helicoverpa punctigera). A native moth whose caterpillars feed on pods and the seeds inside in late winter and spring. Cotton bollworm (Helicoverpa armigera) looks alike and is managed the same way. Check pods weekly and pick off caterpillars. Read more

Redlegged earth mite (Halotydeus destructor). About 1 mm long, with a velvety black body and eight orange-red legs, active from autumn to late spring in southern Australia. Feeding silvers the leaves and can kill seedlings at emergence. Clear nearby capeweed and check young plants often.

Chocolate spot (Botrytis fabae). Reddish-brown spots peppered over leaves, flowers and stems, which can darken and merge into grey-brown patches. It spreads fastest in humid weather at flowering, and spores blow in from old bean residue. Dense sowing makes it worse.

Rust (Uromyces viciae-fabae). Small orange-brown pustules ringed with pale yellow, mostly late in the season as pods fill. It spreads in humid weather above 20°C, and badly hit leaves wither and fall.

Prevention first

• Sow clean seed, since chocolate spot can be carried on it.
• Pull self-sown bean seedlings as they appear.
• Hunt snails and slugs at night, and leave the bed unmulched until seedlings are growing strongly.
• Bin diseased plants rather than composting them or digging them in.

Tips

1. After the last picking, dig healthy plants and roots back into the soil and let them rot for a few weeks. The nitrogen in the root nodules then feeds the next crop.
2. To save seed, grow one line only, since bees cross-pollinate broad beans and the lines can mix.
3. Along a sunny fence, sow a single row and tie the plants to the fence instead of building a frame.