Leaf curl and claw

Which way a leaf curls points to the cause: tips hooking down like a claw usually means too much nitrogen; upward taco means heat or light; downward and heavy means over-watering.

Symptoms

• Claw: very dark green leaves with tips hooking down, soft lush growth.
• Upward curl or taco: heat or light stress.
• Downward curl with heavy leaves: over-watering.
• Twisted new growth: calcium, or aphids on new shoots.
• Battered, clawed leaves in one spot: a fan blowing too hard.

Quick checks

• Which way do the leaves curl, and are they dark green?
• Feed EC and which base feed you're using.
• Canopy temperature.
• Lift test.
• Underside of new leaves for pests.

How to fix it

1. 1
   Feed

   Claw: lower the feed

   Lower the feed strength, and if you're in flower, make sure you've switched from Grow to Bloom.

2. 2
   Environment

   Upward curl: cool and raise

   See Heat stress and Light burn.

3. 3
   Environment

   Fan damage: angle it

   Angle fans so the leaves rustle gently, not blast.

4. 4
   Check

   Twisted new growth

   Check for aphids, then see Calcium deficiency.

Likely causes

• Too much nitrogen, or still on Grow in flower.
• Heat or light too close.
• Over-watering.
• Calcium problems.
• Direct fan blast.
• Aphids or other sap feeders on new growth.

What to avoid

• Don't add more feed to a dark, clawing plant.

Prevention

• Feed to the chart and switch to Bloom on time.
• Gentle airflow.

Monkey products that can help

Bloom A+B

Lower nitrogen than Grow; switching on time in flower helps avoid nitrogen excess.

Follow the flowering chart for the week: equal amounts of Part A and Part B, added separately and never mixed together neat.

View product →

Products support a healthy plant. They don't replace fixing the cause.

When to get help

If curling continues after correcting feed, climate and airflow, email info@monkeynutrients.co.uk with photos.

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