Soybean plants, the humble legume renowned for its versatility in both culinary and agricultural worlds, are an increasingly popular crop for UK gardeners, particularly for those with polytunnels or greenhouses.
While traditionally grown in warmer climates, recent years have seen an interest in growing soybeans in the UK, where polytunnels offer a perfect environment to protect the plants from unpredictable weather.
Growing soybeans at home offers a sustainable alternative to commercially grown soy, which is often linked to deforestation, monocultures, and overuse of chemicals. Large-scale soybean production contributes to environmental degradation, with much of the crop used for animal feed rather than human consumption.
By growing soy in your own garden or polytunnel, you avoid these environmental concerns, reduce your carbon footprint, and have full control over the growing process, ensuring it’s organic and free from harmful chemicals.
Homegrown soybeans also reduce food waste, as you can harvest them when needed and enjoy fresh, nutritious beans without preservatives. It’s a rewarding way to support sustainable food systems and take responsibility for the environmental impact of your food choices.
This guide will take you through every step—from choosing the best varieties to harvesting your first sustainable soybean plant crops.
Choosing The Best Soybean Varieties
When selecting soybean varieties for UK cultivation, it’s essential to choose varieties that are well-suited to cooler, shorter growing seasons. Soybeans generally require a warm growing period, but in the UK, your best bet is to choose early-maturing and cold-tolerant varieties. Popular varieties include:
- Early Group Varieties (Group 00 to Group 2): These varieties mature quickly and are ideal for the UK’s shorter summers. They typically have a growing season of around 120-140 days, making them perfect for harvesting before the first frosts.
- ‘Shirohie’ Soybean: This is a popular variety in the UK for polytunnel gardening. It matures early and offers excellent yields, even in cooler climates.
- ‘Tokyo’ Soybean: Another early-maturing variety, Tokyo is known for its cold tolerance and robust growth even in less-than-ideal weather conditions.
- ‘Soya Tardiff’: Known for its high yield potential and reliability in the UK climate, it is also suitable for polytunnel environments, offering flexibility and resilience.
Preparing the Ground
Soybeans thrive in well-drained, fertile soil with a pH between 6.0 and 7.0. Before planting, it’s important to prepare the ground thoroughly to provide the best possible start for your soybeans.
- Clear the Area: Remove any weeds, debris, or old plant material from the soil. Weeds can compete with the soybeans for nutrients and space.
- Soil Enrichment: Soybeans, like other legumes, have the ability to fix nitrogen in the soil, which improves soil health over time. However, they still benefit from rich, well-draining soil. Incorporate organic matter like compost or well-rotted manure to improve soil texture and fertility.
- Soil Testing: Conduct a soil test to determine nutrient levels and adjust accordingly. If your soil is acidic, adding lime will help raise the pH to a more suitable level for soybeans.
- Tilling: Gently till the soil to a depth of 4-6 inches (10-15 cm) to loosen the soil and create a good seedbed. This also helps with water retention and root penetration.
Sowing Soybeans
Soybeans are best started in early spring, once the danger of frost has passed and the soil temperature is consistently above 10°C (50°F). However, for those growing in polytunnels, this can be earlier, around mid-April, as the controlled environment will provide protection from late frosts.
- Soybeans should be planted in rows about 15-30 cm apart, with seeds spaced around 5 cm apart within each row. This allows enough space for the plants to spread out but not so much that they become overcrowded.
- Sow seeds about 2-3 cm deep. This ensures that the seeds are properly covered, preventing them from drying out or being disturbed by the wind.
Tip: Some gardeners recommend soaking soybean seeds in water for a few hours before planting. This can help accelerate germination, especially in cooler soil conditions.
Soybean Plant Growing Requirements
Once your seeds are sown, it’s time to focus on ensuring the plants have the best growing environment.
Soybeans are sensitive to temperature fluctuations. Ideally, you want daytime temperatures of 20-30°C and night-time temperatures above 10°C.
Polytunnels offer a great way to maintain a stable growing environment, particularly during cooler nights or unpredictable weather, though cloches or additional row covers may be required during the early stages of growth.
Soybean plants can grow tall, so providing support may be necessary, especially in areas with strong winds outside of a polytunnel. Use bamboo canes, netting, or trellis systems to support the plants as they grow taller. This will help the plants stay upright, allowing for better air circulation and sunlight exposure.
Plant Care:
Once your soybeans have sprouted and are establishing their roots, it’s time to focus on proper care.
Watering Soybeans
Soybeans need consistent moisture, especially during their flowering and pod-setting stages. However, they don’t like wet feet, so it’s essential that the soil is well-drained. Polytunnels can help manage watering as they offer some protection against rain, but you still need to ensure that the soil doesn’t dry out.
Water regularly, aiming for deep watering rather than frequent shallow watering. Aiming for around 1-1.5 inches (2.5-4 cm) of water per week during the growing season will help promote strong, healthy plants.
Applying mulch around the base of the plants helps retain moisture, suppresses weeds, and keeps the soil temperature stable.
Fertilizing Soybeans
Soybeans are relatively low-maintenance in terms of fertilization. As a legume, they fix nitrogen in the soil, so they don’t require high levels of nitrogen fertilizers. A general-purpose organic fertilizer or compost added at planting time is usually sufficient.
- Avoid Over-Fertilizing: Too much nitrogen can lead to excessive leaf growth at the expense of pod development. Stick to moderate fertilization.
Supporting Plants
Soybean plants need sufficient space to grow, especially in the early stages of development. For best results, you should support them as they grow by using stakes or a trellis system.
In polytunnels, vertical gardening can be an effective way to manage space. Train the soybean plants upward to reduce the space they take up on the ground.
Regularly check for any damaged or overcrowded branches and prune accordingly to improve airflow.
Harvesting
Soybeans for edamame are harvested while still young and green, typically when the pods are full but before they harden. On the other hand, mature soybeans (for use in soy milk, tofu, or dried beans) are left to ripen until the pods are dry and the beans inside rattle.
The key to successful harvesting is timing. Depending on whether you’re growing soybeans for edamame or mature beans, your approach will vary slightly.
- Edamame Harvesting: Edamame soybeans should be harvested while they are still green and tender. Check the pods regularly, and harvest when the pods are full but still green (around 70-80 days after sowing). You should be able to feel the beans inside the pods.
- Mature Soybean Harvesting: For mature soybeans, allow the pods to dry on the plant. This may take up to 140 days depending on the variety. Once the pods are dry and the beans rattle inside, it’s time to harvest. Use pruning shears to carefully cut the plants at the base.
- Post-Harvest Drying: After harvesting, soybeans for mature use need to be dried further before storing. Hang the plants in a dry, well-ventilated area, or place the beans on trays to fully dry.
Troubleshooting Problems
Growing soybeans can present a few challenges, especially in a UK climate. Here’s a rundown of common issues and how to tackle them:
- Poor Germination: If your seeds aren’t germinating, the soil may be too cold. Ensure the soil temperature is above 10°C (50°F) before planting. Consider pre-soaking seeds to aid germination in cooler soil.
- Yellowing Leaves: If the leaves of your soybean plants turn yellow, this could be a sign of nitrogen deficiency. While soybeans fix their own nitrogen, you might want to add organic compost if the soil is nutrient-poor.
- Frost Damage: One of the biggest threats to soybeans in the UK is late spring or early autumn frost, which can severely damage or even kill the plants. Soybeans are particularly sensitive to frost, especially when they are in their flowering or pod-setting stages.
The best way to avoid frost damage is to grow your soybeans in a polytunnel, which provides protection from late frosts during the spring and autumn. If frost is forecasted and your soybeans are still young or vulnerable, consider covering them with fleece or cloches for extra protection.
Pest and Disease Control
Soybeans are prone to a few pests, such as aphids, whiteflies, and caterpillars, as well as diseases like powdery mildew and rust. In a polytunnel, the controlled environment can reduce the risk of certain diseases, but it’s still important to keep an eye out.
Use organic pest control methods like neem oil or insecticidal soap to tackle infestations only as a last report. Focus primarily on boosting biodiversity and use of barriers for pest control. Encouraging natural predators like ladybirds can help keep aphid populations in check, for example.
For the prevention of disease, maintain good airflow by spacing plants adequately and removing any infected foliage. Avoid wetting the foliage during watering to reduce the risk of fungal diseases.
Are Soybeans Good For You?
Soybeans are packed with health benefits. They are an excellent source of plant-based protein, making them an essential part of vegetarian and vegan diets.
Rich in essential fatty acids, vitamins, and minerals, they are good for heart health, weight management, and supporting bone health. Soybeans also contain phytoestrogens, which are plant compounds that can help balance hormones.
Using Soy Beans
Once your soybeans are ready for harvest, they can be cooked and used in a wide variety of culinary dishes. From soy milk to tofu, tempeh, and edamame, the possibilities are endless. Soybeans can also be roasted, used in salads, soups, and even baked goods. For those interested in home-preserving, soybeans can be dried and stored for long-term use.
Is soy poisonous?
While some people are concerned about the effects of soy, particularly regarding allergies or its content of phytoestrogens, soybeans are generally safe to eat for the majority of people. For those with soy allergies, however, alternative legumes should be considered.
There is no evidence to suggest that consuming moderate amounts of soy is harmful to health for most individuals.
Want to grow other types of beans? Try these guides:
FAQs
How should soybeans be harvested?
Soybeans are ready for harvest when the pods are fully mature and dry. The plant will turn yellow, and the pods will be firm when squeezed. Harvesting is best done when the beans inside the pods rattle.
Can soybeans be grown in containers?
Yes, soybeans can be grown in containers, particularly for those with limited space. Ensure the container is large enough (at least 5 gallons) to accommodate the plant’s root system and provide sufficient drainage.
What are some tips for achieving high yields in soybean farming?
To achieve high yields, select early-maturing varieties, ensure the soil is rich in nutrients, provide consistent water and care, and protect your plants from pests and diseases. Supporting your plants properly and maintaining good airflow will also improve yields.
Sources
Marten, E., (2024) 20 types of beans and how to cook them. BBC Good Food. [online] Available at: https://www.bbcgoodfood.com/howto/guide/types-of-beans-and-how-to-cook-them
