Bush beans
Phaseolus vulgaris
Also known asGreen beans · String beans · Snap beans · French beans · Haricots verts
Environment
The bounded range this crop tolerates. Strict on light; outside the DLI band, yields drop sharply.
Climate and zones
- USDA zones
- 10–13 (winter low around -1°C)
- Frost
- frost sensitive (dies at first frost)
- Season
- warm (summer, frost-sensitive)
Growing systems
Root mass: moderate.
Growing media
| Medium | pH effect | Retention | Bacterial surface |
|---|---|---|---|
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| Perlite (Expanded volcanic glass) | neutral / inert | very low | low |
| Soil-based mix (Potting soil) | varies | high | high |
Nutrient demand by stage
NPK ratios are relative weights. EC targets shift through the plant's life.
| Stage | N | P | K | EC (mS/cm) |
|---|---|---|---|---|
| seedling | 1 | 1 | 1 | 1 |
| vegetative | 2 | 1 | 2 | 1.7 |
| flowering | 1 | 2 | 3 | 2 |
| fruiting | 1 | 2 | 4 | 2 |
Companion-growing notes
- Heavy uptake of potassium. Co-grown crops with the same demand will end up deficient even at "correct" EC.
- High transpiration. Regular reservoir top-ups needed during fruiting.
Aquaponics suitability
Compatible
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 moderately successful hydroponic crop. The bush habit means no trellis is needed, keeping the system simple. EC 2.0-3.0 mS/cm. pH 5.8-6.5. Temperature: 18–28°C (warm-season crop; growth stops below 15°C). Moderate to high light (DLI 16-22 mol/m2/day). DWC, media beds, or Dutch bucket systems all work. Beans are legumes that fix nitrogen through root nodule bacteria (Rhizobium); in hydroponic systems without soil, these bacteria may be absent, so the plants rely entirely on the nutrient solution for nitrogen. From seed to first harvest: 50-65 days. Harvest snap beans when pods are pencil-thick and snap cleanly; delay causes tough, stringy pods. Bush beans set most of their pods within a 2-3 week window, then production declines. Succession plant every 3-4 weeks for continuous harvest. Each plant produces roughly 200–400 g of pods. Common issues: bean beetles (in open greenhouses), powdery mildew (improve airflow), and blossom drop (caused by heat stress above 32°C). For aquaponics, bush beans grow well in media beds and add visual variety alongside leafy greens.