Broad Beans
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Overview:
Broad beans double as a vegetable crop and a green manure crop by returning nitrogen back into the soil, through rhizobium bacteria nodules on their roots (white lumps clustered around the roots).
To create this green manure, cut the stem/s to ground level after harvesting, and leave the roots in place.
Broad beans grow best in rich, moisture retentive, well-drained soil, and a sunny situation sheltered from winds.
They do not like acid soils so check soil pH prior to planting out.
Prepare the planting site by digging in copious amounts of well-rotted manure.
Do not add nitrogen to the soil this causes the plants grow too tall and spindly.
To speed up germination, soak the beans for up to 24 hours before sowing.
Cultivation:
Week 12:
For an early start, sow seed individually into 75mm (3") pots or root-trainers and place in a cold frame or cool greenhouse to germinate.
Seeds should germinate in about 12-14 days from sowing.
Week 15:
Prick out early sowings that have been sown in trays / boxes.
Week 17:
Prepare seed beds now, or sooner if conditions allow by digging in well-rotted manure.
Level the surface of the bed and rake in bonemeal fertiliser at a rate of 75gms (3oz) per sq.m.
Week 18:
Sow seed 200mm (8") apart in 75mm (3") deep drills, in rows 600mm (24") apart.
Seeds should take about three weeks to germinate subject to the weather.
Week 20;
Plant out pot grown seedlings 200mm (8") apart in rows 600mm (24") apart.
A couple of tips; grow the plants in double rows, and they will support one another.
If growing in an exposed area, or if you find tall plants are tending to lean over, push canes in around the plants and link them with string to keep the plants upright.
Week 21>:
Water crops in dry weather to ensure they continue to develop well.
Week 25-28:
Remove the top three inches of the growing tip from each plant to deter blackfly.
An alternative time to do this is after five sets of flowers have set.
These black aphids overwinter on shrubs and migrate to beans in spring.
If the above treatments fail to prevent their presence, treat them as soon as they are seen.
Organic gardeners; spray insecticides based on derris, fatty acids, plant and fish oil or pyrethrum to the underside of foliage.
If this fails, consider using a synthetic insecticide containing bifenthrin.
Week 27-35:
Around this time the beans should be ready for harvesting.
Small beans are tender and delicious but, if picked when tiny, you will end up with a very small crop.
Generally, beans stay in good condition in their pods for several weeks, but don't delay picking for too long or their skin will toughen.
Save money by leaving a few pods on plants to fully ripen, and keep the seed to sow next year.
After harvesting is complete, cut the plants down to ground level, leaving the roots intact to release their 'nitrogen' content into the soil.
Week 45:
For an early crop next year, sow an autumn sowing variety in open ground.
Be prepared for spring frosts by having cloches or fleece available to throw over young plants as the needs arises.