How to Grow Soybeans in the Garden or Field (and for Edamame)

Soybeans are warm-season legumes that fix their own nitrogen, so they need little fertilizer. Gardeners grow them mainly as edamame (green beans eaten from the pod), farmers for dry beans used for oil, feed and tofu. Plant after frost in warm soil (at least 15 °C / 60 °F), keep weeds down early, and harvest edamame when pods are plump or dry beans when pods turn brown and rattle.

Edamame or Dry Soybeans?

• Edamame varieties ('Midori Giant', 'Envy', 'Butterbean'): large, sweet seeds, harvested green.
• Field soybeans: chosen by maturity group matched to latitude; group 00–I for the north, IV–VII for the south.

Planting

Sow 2.5–4 cm (1–1.5 in) deep, 5–10 cm (2–4 in) apart in rows 40–75 cm (15–30 in) apart. In gardens, rows 45 cm apart are typical. Soybeans can also grow in containers at least 30 cm deep.

Inoculation

Where soybeans have never grown, coat seed with Bradyrhizobium japonicum inoculant so roots form nitrogen-fixing nodules.

Care

Keep weeds out for the first 4–6 weeks, water during flowering and pod fill, and avoid nitrogen fertilizer.

Harvest and Yield

Edamame is ready 80–100 days after sowing; dry beans 100–150 days. Field yields typically reach 2.5–4 t/ha (about 40–60 bushels per acre).

All Soybean Growing Guides

• When to plant soybeans
• Soybean seeding rate and spacing
• Soybean inoculation
• Soybean pests and diseases
• When to harvest soybeans and edamame
• Soybean yield per acre

Frequently Asked Questions

How long do soybeans take to grow?

About 80–100 days for edamame and 100–150 days for dry beans.

Can you grow soybeans at home?

Yes, in a sunny bed or large containers; edamame varieties are best for gardens.

Do soybeans need fertilizer?

Little nitrogen; they fix their own. Phosphorus and potassium may be needed on poor soils.