Life & Style
Broad beans have long suffered the curse of being overcooked, but steamed to perfection these plump pale green beans are deliciously sweet and nutty.
Even if I can't convince you of their culinary merits, they're an excellent crop to grow as green manure. Broad beans are legumes, which means they fix their own nitrogen and can therefore replenish the soil of valuable nutrients.
Broad beans are cool-season plants, so sow them now, and thereafter successively, and you'll have a crop from late winter or early spring. The plants tolerate frosts, although bear in mind that heavy frosts at flowering will destroy flowers. That shouldn't devastate your crop though; flowers will grow again from other flowering nodes.
If you're reading overseas books, you'll often see broad beans referred to as faba beans, which comes from their botanical name Vicia faba, or fava beans. They're an important food crop worldwide because they're very nutritious, being high in dietary fibre, complex carbohydrates, protein, copper, iron, manganese, folate, phosphorus, potassium and Vitamins A, B, C and K. The beans, if not eaten fresh, may be dried and ground into flour. In fact, because broad bean flour is high in Vitamin C, it can be added to sourdough starters to speed up the fermentation process.
Sow broad beans directly in the garden. Choose a sunny spot with deep, well-drained soil.
A humus-rich soil is ideal but avoid nitrogen fertilisers. Remember, broad beans fix their own; too much nitrogen results in lots of leaves but no pods. Sprinkle sulphate of potash over the soil and water it in, then leave your soil for a week or two before planting.
If your soil is acidic (broad beans prefer a neutral to alkaline soil), throw in some lime at planting time (or preferably a few weeks before).
Set up a trellis system or insert stakes before planting so that the roots of your plants are not damaged down the track. The easiest method is to secure stakes around your bed and run twine from stake to stake.
Broad beans are traditionally planted in double rows, running north to south to ensure the plants get adequate light. Space the two rows at least 60cm apart, with each seed about 20cm apart and 3cm deep. If you want more than two rows, plant another pair of rows at a distance of 1m from your first pair to allow for easy harvesting.
If the plan is to collect some seed from plants at the end of the season for planting again next year, bear in mind that broad beans cross-pollinate and therefore the seed you collect may not be true to the variety you originally sowed. Commercial growers who save seed for next season's crop, or for selling, sow their crops in separate blocks at least 500m apart to prevent cross-pollination. In the home garden it's not really a big deal, unless you specifically want to grow a certain variety.
Sow seeds every 3-4 weeks so that your crop doesn't mature all at once. Or plant different varieties. The long pod varieties, such as `Exhibition Long Pod', reaches maturity in 18-25 weeks (126-175 days). `Dwarf Early Green' (from kingsseeds.co.nz) on the other hand, matures quickly, so harvesting may take place in as little as 75 days after sowing. The quick maturing varieties are also better for sowing at the end of the season (mid winter for temperate areas, early spring for cold areas with low summer temperatures), as broad beans stop producing flowers in warm temperatures.
As seedlings emerge, protect them from hungry birds. My favourite makeshift barrier to birds is a row of upturned hanging baskets placed over seedlings.
Plants generally grow between 1.2m and 1.5m high, though dwarf varieties may grow around 50-60cm, which means staking may not be necessary.
Flowering signals the start of active growth, so it's essential adequate moisture is provided to plants at this time. If rains are scarce, ensure watering is frequent. Continue watering regularly until 75 per cent of the pods, if left on the plant for collecting seed, turn black.
Black aphids may be a nuisance in spring, not just because they're ugly but because they spread diseases. Blast them off with the hose – or for persistent pests, spray with a suitable insecticide.
Fungal diseases such as rust and chocolate spot may also occur after humid weather or mild, wet conditions. With chocolate spot you'll first notice small reddish-chocolate brown spots on the lower leaves. If conditions continue to favour the fungus, the disease will spread, the spots turning into large patches. Leaves and flowers will eventually drop off.
Rust, another fungus, is characterised by orangey-brown spots on the leaves and stems. If you disturb the orange pustules, the powdery spores erupt, releasing with a puff into the air. Severe infestation will cause leaves to drop and lower yield.
Good hygiene is the best preventative for both these diseases. As soon as you see signs of disease, remove affected plant material and bin or burn it. Clear away any leaf debris on the ground to prevent spores from overwintering, and practise crop rotation. Don't plant your broad beans in the same spot within four years, and make sure there is adequate spacing between rows to allow good air circulation. Cramming plants close together raises humidity levels, which encourages disease. You can also use a copper-based fungicide as soon as symptoms appear to contain the spread.
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