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Tarragon Hydroponic Problems & Fixes

True French tarragon is completely sterile - any packet labelled 'tarragon seed' is Russian tarragon with almost no flavour. French tarragon must be propagated from cuttings.

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Tarragon grown hydroponically encounters flavourless plants from wrong variety, magnesium deficiency, and rootbound decline as its most common problems. Understanding the plant's core thresholds - pH 6.0-7.0, EC 1.0-1.8 mS/cm, water temp 18-22°C, and 12-14h of daily light - helps diagnose problems before they become crop failures.

Quick-Reference Thresholds

| Parameter | Target Range | Warning Sign if Low | Warning Sign if High | |-----------|--------------|--------------------|-----------------------| | pH | 6.0–7.0 | Fe/Mn lockout | Nutrient unavailability | | EC (mS/cm) | 1.0–1.8 | Slow, thin growth | Leaf scorch; stress | | Water Temp (°C) | 18–22°C | Slow root activity | Root disease risk | | Light (h/day) | 12–14h | Leggy, low-oil stems | No issue |

Common Problems & Fixes

| Symptom | Root Cause | Fix | |---------|------------|-----| | No anise/tarragon flavour at all | Almost certainly Russian tarragon grown from seed - contains negligible estragole | Discard and replace with verified French tarragon cuttings from a reputable herb nursery | | Yellowing of lower older leaves | Mg deficiency - relatively common in tarragon | Add Mg at 20-30 ppm; check pH is not causing Mg lockout | | Declining production over time | Rootbound - tarragon declines significantly when pot-bound in net cups | Divide the root mass; trim to 30-40% and replant; tarragon benefits from division every 3-4 months | | Slow establishment of new cuttings | Cuttings need 3-4 nodes and warm water above 18°C for root initiation | Use 8-10cm cuttings with 3-4 nodes; keep in water at 20-22°C until roots are 2-3cm | | Wilting despite adequate nutrition | Root rot from over-saturation | Reduce irrigation frequency; check pump cycle timing |

Normal vs. Worry: What to Watch

  • Normal: Glossy, narrow, lance-shaped leaves on French tarragon - narrower than Russian tarragon.
  • Normal: Slow early establishment from cuttings - 2-3 weeks to see vigorous new growth is normal.
  • Worry: Completely no anise flavour after weeks of growth - Russian tarragon; replace immediately.
  • Worry: Yellowing spreading from leaf margins inward on older leaves - Mg deficiency; supplement immediately.
  • Worry: Production clearly declining despite healthy-looking leaves - rootbound; divide the clump.

Prevention Checklist

  • [ ] Source French tarragon cuttings only from verified culinary herb nurseries - never grow from seed
  • [ ] Include Mg at 20-30 ppm in nutrient formula; tarragon is prone to Mg deficiency
  • [ ] Divide root mass every 3-4 months to prevent rootbound decline
  • [ ] Run intermittent irrigation - 15 min on, 45 min off; tarragon dislikes constant saturation
  • [ ] Check pH every 3 days; maintain 6.0-6.5
  • [ ] Keep EC at 1.0-1.4; avoid over-feeding
  • [ ] Harvest by cutting stems to 10-15cm from crown - do not strip to bare stems