High humidity (damp air)

Humidity above your week's chart range. It slows drying, invites powdery mildew and grey mould, and matters most in late flower.

Symptoms

• Humidity above the chart range for your week, especially at night.
• Condensation on tent walls after lights-off.
• Medium slow to dry; musty smell.
• Powdery mildew or grey mould appearing.

Quick checks

• Check humidity at night as well as day.
• Look for condensation after lights-off.
• Check the extractor and filter aren't blocked.

How to fix it

1. 1
   Environment

   Extract harder

   Increase extraction and keep air moving through the canopy.

2. 2
   Environment

   Steady the night

   Keep nights within about 5–8 °C of the daytime figure to cut condensation.

3. 3
   Environment

   Dehumidify if needed

   Add a dehumidifier if extraction alone can't hold the chart range (it adds heat, so only run it if you need it).

4. 4
   Physical

   Thin and tidy

   Space plants, remove dead leaves and cover reservoirs.

Likely causes

• Extraction too weak or set too slow.
• Big temperature drops at lights-off.
• Crowded canopy and lots of transpiring leaves.
• Wet floor, open reservoirs or drying plants in the same space.

What to avoid

• Don't foliar spray in late flower.
• Don't let humidity creep up overnight in flower.

Prevention

• Follow the chart's falling humidity in flower.
• A hygrometer at canopy height.

Monkey products that can help

Stress

Silicon can help the plant's resistance to mildew. Support only; climate control is the fix.

2 ml per 10 L every week. Always add it to the water first and mix thoroughly before adding anything else.

View product →

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

When to get help

If humidity stays high with full extraction, email info@monkeynutrients.co.uk with your tent size and fan.

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