Mizuna Nutrient, pH & EC Guide for Hydroponics
Mizuna germinates and grows at reservoir temperatures as low as 10°C - cold growing concentrates mild sweetness and reduces glucosinolate sharpness compared to warm-grown plants.
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Mizuna is a feathery, mild-flavoured Japanese brassica that occupies an interesting space in hydroponic production: it is unusually cold-tolerant for a salad green, grows rapidly under ideal conditions, and its flavour profile is actually improved by cooler growing temperatures. Unlike arugula or mustard greens where peppery bite is the target, mizuna's appeal is in its mild, slightly sweet flavour - which is best preserved at the lower end of its temperature range.
pH and EC Targets
| Stage | pH | EC (mS/cm) | PPM (approx) | Notes | |-------|-----|------------|--------------|-------| | Seedling | 5.5–6.8 | 0.5–0.8 | 250–400 | Fast germination at 15–20°C; cool start acceptable | | Vegetative | 5.5–6.8 | 0.8–1.2 | 400–600 | Moderate EC; excess nitrogen produces floppy feathery stems | | Mature | 5.5–6.8 | 1.0–1.6 | 500–800 | Hold steady; harvest before bolting at 35–42 days |
Note on PPM: Values above use a 500 conversion factor (EC × 500 = PPM). Some meters use 700 - multiply by 1.4 to convert.
Key Nutrients
| Nutrient | Role in This Plant | Deficiency Sign | Correction | |----------|-------------------|-----------------|------------| | Nitrogen (low-moderate) | Structural leaf growth; excess nitrogen produces oversized floppy feathery leaves with poor texture | Pale yellowing from base upward (deficiency); oversized limp leaves (excess) | Target N at 80–120 ppm NO3-N; deliberately conservative to maintain leaf texture | | Sulfur | Mild glucosinolate production for characteristic gentle brassica bite | Loss of even mild flavour character; bland leaves | Maintain SO4 at 30–50 ppm; lower than mustard or arugula as intensity is not the goal | | Calcium | Standard brassica Ca requirement; 120–180 ppm | Brown papery tip burn on inner leaves | Maintain Ca at 120–180 ppm; Ca:Mg ratio approximately 3:1 |
Deficiency Identification
- Limp, oversized, feathery leaves with poor texture: Excess nitrogen combined with EC above 1.6. Reduce EC and nitrogen concentration. Mizuna's fine-cut leaves collapse under excess nutrient pressure.
- Yellowing from oldest leaves upward: Nitrogen deficiency. Increase total EC carefully, maintaining the conservative nitrogen approach.
- Tip burn: Calcium transport limitation. Add airflow; check Ca at 120–180 ppm.
- Early bolting: Temperature above 22°C or day length above 14 hours. Mizuna is more heat-sensitive than many Asian brassicas.
Feeding Schedule Notes
Mizuna is extremely fast under ideal conditions - baby-leaf harvest at 21–25 days is achievable at 18°C. Start at EC 0.5–0.8 and step up to 1.0–1.2 after the first week; EC above 1.6 is counterproductive and produces the limp oversized leaves that undermine mizuna's culinary appeal. For flavour quality, consider running the reservoir at 10–14°C: growth slows to approximately 60% of the rate at 18°C, but the resulting leaves are distinctly sweeter and more mildly flavoured - a worthwhile trade-off for salad-mix production where gentle character is valued. Succession-sow every 2–3 weeks. Full reservoir changes every 7–10 days.
Research note: Mizuna grows at reservoir temperatures as low as 10°C; at 10–12°C growth slows to ~60% of the rate at 18°C but cold concentrates mild sweetness and reduces glucosinolate sharpness.