Soybean: cultivation, harvest & uses

If you want to enjoy fresh edamame and homemade tofu, you can grow soy yourself. We give tips on choosing the variety, sowing and harvesting soybeans in your own garden.

The soybean (Glycine max) can be used in many ways and can be grown in your own garden or on the balcony. With us you can find out everything about planting, caring for and using soy.

Soybean: Origin and Characteristics

The soybean originally comes from northern China and Japan and is the most important protein and oil crop in the world in terms of acreage. It belongs to the family Fabaceae and is closely related to pea (Pisum sativum), lens (Lens culinaris), lupine (Lupinus) and Bean (Phaseolus vulgaris) related. Soy plants reach a height of 40 to 100 cm, depending on the variety and conditions. The very hairy, annual plants form a deep taproot. Soy, like most butterflies, lives in symbiosis with subterranean, knot-forming root bacteria. These soy-specific nodule bacteria (

Bradyrhizobium japonicum) settle in round knobs on the roots and collect nitrogen from the soil air. The bacteria exchange this oxygen with the sugar that is produced during photosynthesis in the soybean plant. In this way, they make a significant contribution to the fertilization of the plant.

The leaves of soy are pinnate in three parts and, like the stems, are very hairy. The self-fertilizing, white or pale purple small flower appears during the flowering period of the soy between May and July. After fertilization, elongated, brown-haired pods with two to three oval-round seeds each form. Young, immature harvested seeds including the pod are called edamame. The word comes from Japanese and roughly means "bean on a branch". Between September and October - when the seeds are ripe - the entire soybean plant gradually dies. The dry pods eventually burst open and release the seeds and spread them around the area. Soybean seeds can be creamy white, beige, brown, green, black or piebald, speckled and marbled.

The best soybeans

All soybean varieties can be harvested for edamame as well as dry beans. The only decisive factor for cultivation in Central Europe is early ripening. Early soybean varieties ripen 75-100 days after sowing between August and September, and later in October. With the latter, there is a risk that the soybeans will not ripen at all in cool and rainy summers. Therefore, only very early to early varieties are recommended for soy cultivation in Germany.

• ‘Agate‘: Very early soybeans with fawn to dark brown seeds. The small plants are abundant and can be harvested after 90 days.
• ‘Chiba Green‘: Tasty edamame soybeans with only a very short development time. Harvesting is possible as early as 75 - 90 days after sowing.
• ‘Envy‘: Up to 80 cm high soybeans with shiny green kernels. The unripe pods can be harvested from August, the dry kernels from the end of September to October.
• ‘Fiskeby V‘: Very early, light yellow soy variety for crunchy and sweet-tasting edamame with harvest beginning in August and dry beans from October.
• ‘Green Shell‘: Early and firm edamame soybeans with a short development time of around 100 days. The harvest extends from mid-August to the end of October.
• ‘Hokkaido Black‘: A vigorous and bushy variety of soy with glossy black seeds, adapted to cooler areas. In addition to edamame, they are served as a Kuromame dessert for the Japanese New Year celebrations.

Growing soybean plants in the garden

The ideal location for soy cultivation is in a sunny spot on quickly warming, permeable and water-storing soils. The pH should be between 6.5 and 7. Soy can be sown outdoors from a soil temperature of over 10 ° C, which is usually reached between April and mid-May. Since soy needs a lot of time to ripen, it should always be sown before June. A preculture on the window sill from April with planting in May is also possible. The sowing depth is 3 - 4 cm, because soybeans are strictly dark germs. The distance between the plants should be 10-15 cm, that between the rows 30-50 cm. At temperatures of 12-20 ° C, germination takes about 10-20 days.

If you want to grow soybeans on the balcony or generally cultivate them in a planter, you should choose a pot with a capacity of at least 5 l with good water drainage. Fill the pot with a good quality potting soil like ours Plantura organic universal soil and then sow soy seeds in it. Three to four soy plants can be grown in a 5 liter pot.

tip: Not only for growing soybeans in pots, but also to improve too heavy or too Our peat-free, compost-rich and sustainably produced in Germany is suitable for sandy soils Potting soil.

For particularly good growth and high yields, it is advisable to inoculate the soybeans with their natural symbiotic partners, the nitrogen-fixing nodule bacteria, before sowing. The microorganisms are available as an aqueous solution together with a sugar-rich adhesive mixture in small quantities for hobby gardeners. Sugar and nodule bacteria are mixed in a spray bottle and then applied to the soybeans. The inoculated soybean seeds should now be planted quickly, as the bacteria are extremely light-sensitive and quickly die when exposed to sunlight.

Soybeans are good previous crops because they accumulate nitrogen in the soil. After them, strongly eating vegetables such as tomato (Solanum lycopersicum) or zucchini (Cucurbita pepo subsp. pepo convar. giromontiina) can be grown. Soybeans themselves should only be planted in the same location every three years.

Summary: growing soy yourself

• Ideal location: warm and sunny on well-drained, water-storing soils.
• For optimal growth: spray the soybean seeds with nodule bacteria shortly before sowing.
• Sow from April on the window sill or directly outside from a soil temperature of 10 ° C by the end of May at the latest.
• Sowing depth: 3 - 4 cm, planting distance: 10 - 15 cm, distance between the rows: 30 - 50 cm.
• At temperatures of 12-20 ° C, germination takes place after 10-20 days.
• In the case of preculture, planting from mid-May in a bed or tub in high-quality potting soil.
• Crop rotation: plant soybeans only every 3 years on the same site.

Proper care

Soybeans hardly need any care after germination. Fertilization is not necessary if enough nodule bacteria have settled on the roots. The water supply plays an important role until a sufficiently large root system has developed. Additional irrigation may therefore also be necessary in the bed, especially when the soy blooms between June and August. Another maintenance measure at the beginning is the removal of weeds until the soybean plants have formed a dense stand. A layer of mulch made from grass clippings and other materials reduces evaporation and can prevent unwanted weeds from growing. At the same time, it provides food for soil organisms and thus promotes the build-up of humus.

Common pests on soy: Soy diseases and pests have so far only occurred rarely in Central Europe. The painted lady caterpillars (Vanessa Cardui) can, for example, occur in nests on soybean plants and cause severe feeding damage. Pigeons and crows like to dig up freshly planted seeds and young seedlings. Young soybean shoots are also a welcome snack for rabbits, hares and deer. A protective, fine-meshed net over the existing structure can help.

Harvest soybeans

The harvest stage for green soybeans as edamame is roughly comparable to that of tender green French beans. The pods should still be completely green and not lignified or fibrous, but the cores inside should already be clearly visible. For most varieties, the edamame harvest begins around 80-100 days after sowing. Do you want to harvest dry soybeans to make your own plant-based drinks or tofu? Then you should wait until the entire soy plant has turned brown. Depending on the variety, this is the case between September and the end of October. Ideally, the dry pods rustle on the plant when touched, which is a sure sign of the beginning of the soy harvest season. Ideally, harvest in the morning when the pods are still damp and tough from the dew. Because dry, ripe pods tend to burst open when harvested. The entire plant is cut off at the bottom with a pair of secateurs and dried for a few days in a sunny, warm place. The seeds are then pitted by hand or threshed in a sack.

Are Soybeans Healthy?

Soybeans are healthy and at the same time filling seeds. 100 grams contain about 150 kcal. Particularly nourishing ingredients of soy are the abundant proteins and fats it contains. The very high protein content of 30 - 50% in soybeans can be used in human and animal nutrition. When dry, soybeans also contain a certain amount of oil, between 18 - 24%. The high unsaturated fatty acid content of soybeans is extremely healthy. The kernels also contain various minerals and vitamins, especially vitamin E, potassium, calcium and magnesium.

Use of soy

Soy is playing an increasingly important role in human nutrition. Numerous meat and milk substitute products for vegetarian and vegan diets are mainly made from soy. In Asian countries, the use of soybean oil for frying and deep-frying is common. Tofu and soy mince can be made from the seeds. However, soybeans also function as a healthy snack when roasted and processed. Fermented soybeans are particularly easy to digest, as soy sauce or in the Japanese dish natto. The young, still green and juicy kernels including the pods are briefly boiled as edamame and then served with salt and other spices.

tip: Incidentally, the so-called "bean sprouts" are not seedlings of soybeans, but of mung beans (Vigna radiata).

Is soy poisonous?

When raw, young soybeans, ripe seeds and all green parts of the plant are poisonous and, if consumed in excess, can cause nausea and vomiting. This applies to humans and pets, with the exception of rabbits. Both edamame and dry soybeans should therefore only be enjoyed after sufficient cooking time or roasting.

the chick-pea (Cicer arietinum) belongs, like the soybean, to the family of the butterfly family and can also be grown on the balcony and in the garden. We give tips on choosing a variety, planting and caring for it.