Spinach
Spinacia oleracea
Also known asEnglish spinach · True spinach · Persian spinach
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 5–9 (winter low around -29°C)
- Frost
- frost hardy
- Season
- cool (spring/fall)
Growing systems
Root mass: moderate.
Growing media
| Medium | pH effect | Retention | Bacterial surface |
|---|---|---|---|
| Rockwool (Mineral wool) | alkaline until pre-soaked | very high | low |
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| Net pot, no medium (Bare-root) | - | - | - |
| 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 | 0.8 |
| vegetative | 3 | 1 | 2 | 2 |
Companion-growing notes
- Heavy uptake of calcium. Co-grown crops with the same demand will end up deficient even at "correct" EC.
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 fast but fussy hydroponic green. EC 1.5-2.5 mS/cm. pH 6.0-7.0. Temperature: 10–20°C (critical: above 22°C, spinach bolts within days; sustained heat is the primary production challenge). Moderate light (DLI 12-17 mol/m2/day; excessive light and long photoperiods trigger bolting). NFT, DWC, raft, or vertical systems. From seed to baby spinach: 3-4 weeks. Full-sized: 5-7 weeks. Succession plant every 2 weeks for continuous supply. Slow-bolt varieties ('Space', 'Renegade', 'Bloomsdale Long Standing') extend the harvest window but can't overcome sustained heat. For year-round production, spinach is a fall/winter/spring crop; summer alternatives include Malabar spinach, New Zealand spinach, or heat-tolerant chard. Downy mildew (Peronospora farinosa f. sp. spinaciae) is the most serious disease; resistant varieties are essential for commercial production. Baby spinach commands $6-12/kg retail and is one of the highest-demand hydroponic salad crops.