Tarragon Nutrient, pH & EC Guide for Hydroponics
True French tarragon is sterile and cannot be grown from seed - any seed sold as 'tarragon' is Russian tarragon with almost no culinary flavour, making propagation method the defining quality decision.
Last updated
Tarragon is unique among culinary herbs in that the only way to grow the correct variety is through vegetative propagation - French tarragon (Artemisia dracunculus var. sativa) is sterile and produces no viable seed. Any seed sold as "tarragon" produces Russian tarragon (A. dracunculus var. inodora), which has almost no culinary value. Beyond this defining fact, tarragon has moderate nutrient needs with an emphasis on low nitrogen for essential-oil concentration.
pH and EC Targets
| Stage | pH | EC (mS/cm) | PPM (approx) | Notes | |-------|-----|------------|--------------|-------| | Cutting establishment | 6.0–7.0 | 0.4–0.6 | 200–300 | Root cuttings in dilute solution; French tarragon roots slowly (3–4 weeks) | | Vegetative | 6.0–7.0 | 1.0–1.4 | 500–700 | Ramp gradually; keep nitrogen at lower bound | | Mature | 6.0–7.0 | 1.2–1.8 | 600–900 | Hold steady; harvest regularly to prevent woody growth |
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 | |----------|-------------------|-----------------|------------| | Potassium | Estragole (methyl chavicol) synthesis - the anise flavour compound that defines French tarragon | Reduced anise character; less intense aroma | Maintain K at 150–200 ppm; increase K:N ratio at maturity | | Nitrogen (moderate, lower bound) | Structural leaf growth; excess dramatically dilutes essential-oil concentration | Pale yellowing (deficiency); large, rapid, flavour-diluted growth (excess) | Target N at 80–100 ppm NO3-N; keep at lower bound throughout | | Magnesium | Occasional interveinal chlorosis on older leaves, particularly under high light | Yellow patches between green veins on mature leaves | Supplement MgSO4 at 0.3–0.5 g/L if chlorosis appears; maintain Mg at 40–60 ppm |
Deficiency Identification
- Absent or very weak anise flavour: Either you have Russian tarragon from seed rather than French tarragon from cuttings, or excess nitrogen has diluted the essential oil. Verify plant source before adjusting nutrients.
- Interveinal yellowing on mature leaves: Magnesium deficiency. Supplement MgSO4 and check Ca:Mg ratio is approximately 3:1.
- Slow growth after cutting propagation: French tarragon roots slowly compared to other herbs (3–4 weeks). This is normal; do not increase EC during rooting.
- Woody, non-productive stems: Tarragon becomes woody with age. Harvest regularly from branch tips and replace plants after 2–3 years with fresh cuttings from the original stock.
Feeding Schedule Notes
Source French tarragon from a reputable herb nursery as rooted cuttings - never from seed. Establish cuttings in dilute solution at EC 0.4–0.6 and expect 3–4 weeks to reliable rooting. Step up to 1.0–1.4 once growth resumes and new leaves are actively emerging. Keep nitrogen at the lower bound throughout the grow cycle - estragole synthesis is suppressed by excess nitrogen in the same way that most essential-oil herbs lose character when over-fed. Harvest 5–8 cm tip shoots regularly to prevent the plant from becoming woody. Maintain solution temperature at 18–22°C; tarragon is not as heat-tolerant as basil and will lose flavour intensity above 25°C.
Research note: True French tarragon (Artemisia dracunculus var. sativa) is sterile - any seed sold as 'tarragon' is Russian tarragon with almost no culinary flavour. Tarragon is entirely propagation-dependent.