Originating from South-East Asia, these beans usually need a long, hot summer of 20–30°C (68–86°F), although some newer varieties can cope in cooler conditions. They are an excellent source of protein and can either be picked and cooked when still green, or left to mature, then dried and stored.
Jobs to do now
- Water regularly
- Keep weed-free
- Harvest immature pods
Month by month
Soya beans can be sown indoors or outdoors, in May or June.
The easiest option is to sow outdoors once the soil has warmed up in late spring, ideally under fleece or cloches.
They like a warm, sunny, sheltered spot, and fertile, free-draining soil. Sow the seeds 5cm (2in) deep, 15cm (6in) apart, in rows 45cm (18in) apart.
You can also sow indoors, in 7.5cm (3in) pots or seedtrays filled with seed compost, setting the seeds 5cm (2in) deep. Water gently, then place the pot or tray in a propagator, or cover with a clear polythene bag, and keep at a temperature of 18–20°C (64–68°F).
Once the seedlings appear, remove from the propagator or uncover, then place in warm, bright location. Move the seedlings into larger pots when roots appear through the drainage holes.
Gradually acclimatise indoor-sown plants to outdoor conditions (harden off), before planting out after all risk of frost has passed.
Choose a warm, sunny site with well-drained but moist soil. Space the plants 15cm (6in) apart, in rows 45cm (18in) apart. Cover the surrounding soil with a thick layer of mulch, such as garden compost, to help retain moisture.
Plants can grow up to 1.2m (4ft) tall, but are usually self-supporting.
Hoe around plants regularly and keep them well watered.
You can harvest the beans either unripe (known as edamame beans) or fully ripe as dried soya beans.
Edamame beans are immature soya beans, harvested in summer while the pods are still green, with plump beans inside. They can either be shelled or cooked in the pods, and must be boiled for at least 10 minutes to destroy any toxins.
Ripe soya beans are ready for harvesting from late September, when the leaves start to fall from the plants, often leaving just brown stems with lots of hanging pods. The pods remain weatherproof during autumn, so you can pick as required.
The beans are easy to store on the plants or in airtight containers.
Soya beans must not be eaten raw – boil them for at least 10 minutes to get rid of toxins.
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