Edamame / Vegetable soybean (Glycine max) growing guide

Quick facts

Category: fruiting
Difficulty: beginner
Days to harvest: 75 to 100 days
Harvest type: single harvest then replant
Spacing: 15 cm between plants

Environment

Temperature: 18–30°C
pH: 6 to 7
EC (hydroponic): 1.4 to 2 mS/cm
Daily light: 22 to 32 mol/m²/day (strict, will fail outside this range)

Climate and zones

USDA zones: 3 to 11 (winter low around -40°C or warmer)
Frost tolerance: frost sensitive (dies at first frost)
Season: warm (summer crops, frost-sensitive)

Viable growing environments:

outdoor in growing season (annual)
unheated greenhouse / hoop house

USDA zone bounds reflect outdoor year-round survival. Anywhere outside the bounded zone range, this crop still grows as an annual in the warm months (outdoor_seasonal), under cover (greenhouse), or indoors under lights.

Growing systems

Edamame works in:

soil bed
media bed (ebb and flow)

Growing media

The substrate the roots sit in. Choice depends on the system (clay pebbles don't fit NFT channels; rockwool isn't used in media beds) and the crop (edamame works in the media listed below).

Medium	pH effect	Water retention	Bacterial surface
Soil-based mix (Potting soil)	varies by source	high	high
Coco coir (Coconut coir)	slightly acidic	high	moderate

Bacterial surface area matters for aquaponics: clay pebbles, lava rock, and pumice double as biofilter substrate. Low-surface media (rockwool, perlite, pea gravel) work in hydroponics but need a separate biofilter in aquaponics.

Nutrient demand by stage

NPK ratios are relative weights at each growth stage; the nutrient mix calculator scales them to absolute grams or ml. EC targets shift through the plant's life: seedlings need a much lighter solution than fruiting adults.

Stage	N	P	K	EC target (mS/cm)
seedling	1	1	1	1
vegetative	1	2	2	1.4
flowering	1	2	2	1.6
fruiting	1	2	2	1.8

Aquaponics suitability

Compatible with typical aquaponics nutrient profiles. Fish waste provides enough nitrogen for healthy growth; supplemental potassium, calcium, and iron may still be needed depending on fish stocking density.

Care notes

A warm-season legume for hydroponic or aquaponic media bed systems. EC 1.5-2.5 mS/cm. pH 6.0-7.0. Temperature: 20–30°C (warm-season crop; frost kills the plant, and cool temperatures below 15°C slow growth significantly). Moderate to high light (DLI 16-22 mol/m2/day). Direct seed into media beds or large containers. As a legume, soybeans fix nitrogen through root nodules (Bradyrhizobium japonicum), but the bacteria may be absent in sterile hydroponic media. Inoculate seeds with soybean-specific inoculant before planting, or rely on nitrogen from the nutrient solution. From seed to edamame harvest: 75-90 days. Harvest when pods are plump, bright green, and beans fill the pod without hardening. The harvest window is narrow (about 1-2 weeks); after that, seeds begin drying and the edamame stage is past. Blanch harvested pods in boiling salted water for 4-5 minutes, then cool quickly. Frozen edamame stores for 6+ months. Each plant produces 50-100 pods. Bush varieties ('Midori Giant', 'Sayamusume') are more practical for confined growing spaces than tall, vining types.

Notable varieties

A starting shortlist of cultivars worth knowing about. Not exhaustive: the seed catalogs list hundreds of named varieties. These are the ones home growers commonly choose between.

Cultivar	Type	Breeder / origin	Days	Notes
Envy	open-pollinated		75	Very early variety (75 days). The variety to grow in zone 4-5 short summers. Smaller pods, decent flavor.
Midori Giant	open-pollinated		80	Japanese-bred standard variety. Large pods, excellent fresh flavor. The default home garden edamame.
Be Sweet 292	open-pollinated	Johnny's Selected Seeds	90	Mid-season, very sweet. Productive. The variety US restaurants and commercial growers prefer.