Grow More Legumes
To improve soil
As Amenity plants
Who hasn’t grown peas or beans at home, and what would a big breakfast be without a splash of baked beans? Legumes are also among some of our most spectacular garden plants, and include the likes of wattles, robinias, and wisterias.
What is a Legume?
All legumes produce seeds in pods. Legumes belong to the Fabaceae family, and taxonomists further divide them into three subfamilies based on flower differences. But as a group, there are a lot of similarities:
• Legumes host colonies of beneficial bacteria on their roots that extract nitrogen from air in the soil and feed it into the plant tissue increasing soil nutrition.
• Edible legume seeds provide many important animal and plant foods - not only peas and beans, but also soy, carob, lentils, lupins, and peanuts.
• Edible legume seeds are a good source of protein and are used to make meat substitute foods such as vegan sausages and burgers.
General Growing Tips
Different species of legume attract specific nitrogen fixing Rhizobium bacteria species. In some soils, there may be a lack of Rhizobia, so commercial edible legume seeds are usually inoculated with them. Another option is to purchase an appropriate Rhizobium strain or group for the legume being sown and to inoculate the seed. Inoculants can be applied using a commercially available adhesive which are supplied with instructions on how to use.
Legumes are ideal in crop rotations because after bearing fruits the plants can be used as green manure to return nitrogen to the soil. Since they return nitrogen, soils they are grown in generally don’t require much fertiliser. Instead, they can be prepared by adding well-rotted compost or manure about six weeks before sowing seed or planting seedlings.
Legumes like moist but not overly wet soils, so the ideal soils have sufficient organic matter to retain moisture yet are free draining. Plants such as beans and peas must be placed sufficiently far apart to allow them to spread without competing together.
Many commonly grown legume crops prefer milder climates and tend to stop growing during very hot weather. However, there are species of beans and peas that come from subtropical and tropical zones, and others that thrive in warmer weather, so it’s a question of growing what suits your local climate.
For the home vegetable garden, the most widely grown beans are usually the common bean, runner bean, and broad bean.
Common beans are also known as green beans, French beans, haricot beans, flageolet, and string beans. They are all cultivars of Phaseolus vulgaris. Most green beans have a compact or bushy growth habit and are referred to as ‘bush beans’, or sometimes ‘dwarf beans.’ Some cultivars have a climbing habit and are known as ‘pole beans.’
Runner beans, Phaseolus coccineus, are climbers. Their striking red flowers make them popular as ornamental vines as well as vegetables.
Broad beans, Vicia faba, have many other names, such as faba beans, fava beans, horse beans, field beans and English beans.
Seeds should be sown singly in rows at a spacing of about 15 cm between seeds. You can always plant a couple of seeds close together and thin out where necessary. If using double rows, leave 25 cm between rows, and a metre between each double row.
Runner beans need to be grown on a fence, trellis, or some other support. You can stagger plantings by several weeks to give more than one crop.
The ideal soil pH is 6.0. A pH below 5.5 will significantly affect growth during early stages.
Common beans are warm-season crops. They grow well in temperatures from around 15°C through to 29°C, depending on the cultivar. Broad beans and runner beans are cooler season crops. They need temperatures in the range of 7°C to 23°C. You can sow broad beans from autumn through to the end of winter, or autumn only in very warm places. Runner beans only grow well in cooler regions. If temperatures get too warm, the flowers may be sprayed with water to encourage fruit set. Common beans may be sown from spring through to the end of summer, or all year round in the warmest climates.
Most beans can be grown in containers with a depth of 30 cm or more. Common bean bush types can be grown as broadacre crops. Both bush and pole types may be grown in raised beds, or in hydroponic systems. With bush types you can also mound up the soil around the base when they are about 30 cm tall.
Climbing varieties do not take up as much room, but trellis or some other form of support is needed since many grow up to 2.5 metres or more. Avoid strong winds or frost.
Watering & Feeding
Beans need plenty of soil moisture, but you should never let them become waterlogged. Only water when the soil becomes dry.
A feed with liquid fertiliser may be applied when the first fruits appear. Phosphorus, potassium, and sulphur levels need to be high, but nitrogen levels should not be as high as with other vegetables. The ratio of nitrogen to potassium should be roughly equal.
Beans are fast-growing so don’t take long until harvest. Pole types are high-yielding beans that can be harvested after about 10-12 weeks.
Usually with beans, the pods are picked before the seeds inside have fully matured. For common beans, the whole pod is picked and consumed. With broad beans, the immature seeds are removed from the pods and eaten.
Sometimes beans are left to mature and dry in the pods, in which case the hardened bean seed is known as a ‘pulse’. Examples of beans grown as pulses include butter beans (lima beans), kidney beans, and mung beans.
Peas are cool-season, frost-hardy, leguminous crops. Peas are grown in temperate regions throughout the world, though they can also be grown at higher elevations or during the cooler seasons in warm regions.
Edible pod peas are cultivars or varieties of Pisum sativum. They include those referred to as ‘snow pea’ or ‘sugar pea’ (Pisum sativum var. macrocarpon), ‘sugar snaps’ (Pisum sativum var. saccharatum), and ‘English pea’ or ‘green pea’ (Pisum sativum var. sativum).
Peas can be categorised as ‘dwarf types’ (or ‘bush types’), ‘medium tall’, and ‘tall types.’ Usually, dwarf types are early, and mid-season types are medium or tall. Late types are tall and fast-growing annual vines that require trellis or other supports.
Peas are propagated by seeds. Soak seeds for 6-12 hours before sowing to enhance germination during summer.
Most peas can be planted in rows with one plant every 8 to 10 cm (up to 15 cm for snow peas and down to 5 cm for sugar snaps). The distance between the rows is usually 60 to 80 cm. For trellis production, rows should be 2 m or more apart. Bush types can be sown a bit closer at 2 to 3 cm spacing thinning to around 7.5 cm once the seedlings are up, and 50 cm between rows.
Climbers need some form of trellis to manage the growth, to keep the pods off the ground, and to facilitate harvesting.
Peas are cool season crops and thrive in cold weather. They favour an average temperature range of 13 to 18°C during growth. The optimum temperature for seed germination is 22°C and germination is inhibited below 5°C. Peas can tolerate frost at early growth stages but it will injure newly opened flowers and young pods. Pods grow best in regions where there is a slow transition from cool to warm weather in spring. As temperatures increase, maturity is hastened, and yield and quality are reduced.
Peas can be grown on most types of soil but prefer well-drained, loose, loamy soil. Clay soils require good drainage. A pH range of 6.0 to 7.0 is optimal for pea cultivation. Liming is recommended for acid soils.
Watering & Feeding
The main nutrient required by peas is phosphorus which is important for early root development and assists with flowering, fruiting, and sugar development.
Like beans, peas need satisfactory soil moisture throughout the life of the crop but don’t grow in waterlogged soils. Flowering, fruit set and pod filling periods are critical stages and care should be taken to irrigate crop at these stages.
Snow peas are harvested approximately 10 days after flowering which is 8 to 12 weeks after planting and may continue for 8 to 10 weeks. Pods are picked when flat and seeds are undeveloped.
Green peas can be harvested once the peas inside are a good size and still tender before they lose moisture.
Sugar snaps are harvested when the pods are fully developed and like a normal garden pea in appearance but still young.
Besides their culinary uses, pea straw is a by-product which makes a nutritious fodder.
Storing Harvested Legumes
Freshly harvested beans and peas will last about a week in a refrigerator if packed into airtight bags or containers. Freezing and drying will prolong storage life.
To freeze legumes, they must be blanched first. This involves boiling them and then cooling in ice cold water. Blanching stops the enzyme activity that will reduce the quality and storage life.
Drying is a cost-effective method to preserve legumes since there is no ongoing power cost from running freezers and minimal material cost unlike canning. Legumes need to be shelled and blanched first. They can then be dried in a dehydrator or oven to remove moisture and increase shelf-life. Dried legumes last for years if stored properly.
Using Edible Legumes
Legumes are consumed in soups, stews, savoury pies, salads, sauces, and spreads, or as side dishes of vegetables. To remove toxins, fresh legumes should be soaked in water for about 12 hours before cooking. A few types of green pea like sugar snaps can be eaten raw.
Under suitable moisture and temperature conditions, legume seeds can be sprouted without soil and eaten as microgreens. They are a highly nutritious raw food, popular in salads and stir fries.
Legumes can also be eaten as dried seeds for healthy snacks. Split grains of peas are used for dal. Fibre and carbohydrates in legumes digest slowly so people feel fuller for longer after eating them.
In vegetarian diets, legume protein may replace meat protein. Ground legumes produce flours. Pea flour is suitable for making breads, pastas, flatbreads, pitas, rolls, buns, and crackers.
Soybeans can be used to make tofu by mixing with water and a coagulant. Japanese silken tofu has a delicate texture and mild flavour whereas Chinese firm tofu can be fried, stir-fried, grilled, baked in casseroles, simmered in stews, and put on skewers.
Fermented soybean products include Tempeh from Indonesia and Miso, a bean paste made of fermented soybeans, sometimes with wheat, rice, or barley.
Soy milk is a good all-purpose, high protein, non-dairy milk made from soybeans. Pea protein milk offers a high protein alternative to soy.
Making Vegetarian Sausages with Legumes
A successful vegetarian sausage must look and feel like a sausage, but it doesn’t need to taste like meat. When it is cut crossways, each slice should hold together, and the casing should peel off easily.
To replicate animal fat and give a juicy taste, moisture content is increased. This can be done using a vegetable oil. starch or gums also add to juiciness but must be used in moderation to avoid the sausage tasting too soft.
The ingredients are stuffed into a synthetic casing, and typically include:
Principal (dominant) material: grains, legumes, potatoes.
Protein source: wheat gluten, tofu, textured vegetable protein (TVP).
Fat: vegetable oil.
Binder: flour, starch, natural gums, flaxseed emulsion.
Show material: nuts, seeds, dry fruit, diced tofu, TVP.
Ingredients: salt, sugar, honey, natural colourings, vegetable stock, spices (cinnamon, nutmeg, cloves, ginger, allspice).
To learn more about growing and using legumes, please see:
Our Edible Legumes eBook @ www.acsbookshop.com
Legume Farming Course – Agronomy IV @ https://www.hortcourses.com/courses/legumes-agronomy-iv-2817.aspx
Legume video at: https://vimeo.com/375571803