Calcium deficiency

Rusty brown spots and twisted, crinkled new growth. Common in coco and with soft or RO water, and often an uptake problem caused by pH or humidity swings.

Symptoms

• Brown, rusty spots on leaves, often on newer growth.
• Twisted, crinkled or distorted new leaves.
• Weak stems and slow growth at the tips.

Quick checks

• Are you in coco, or using soft or RO water?
• Check feed and run-off pH.
• Is Mag Cal in the mix?
• Check day and night humidity.

How to fix it

1. 1
   Check

   Correct pH and climate first

   Check the basics first: feed and run-off pH (5.5–6.5), EC for this week, watering, climate and light. Keep humidity steady within the chart range.

2. 2
   Feed

   Add Mag Cal if you're in coco, soft or RO water

   Use Mag Cal at 1 ml per litre with every feed in coco, or with soft or RO water.

3. 3
   Environment

   Water evenly

   Avoid letting the medium swing between bone dry and soaked.

4. 4
   Monitor

   Judge by new growth

   Give it 3–5 days and look at the newest leaves. Spotted leaves won't recover.

Likely causes

• Coco holding on to calcium (its high cation exchange capacity).
• Soft tap water or RO water with very little calcium.
• pH below 5.5, where calcium uptake suffers.
• Big humidity swings or very high humidity, slowing the water flow that carries calcium.
• Uneven watering or drying out.

What to avoid

• Don't add extra calcium if you're on hard water without checking pH first.
• Don't overdo Mag Cal beyond the stated rate.
• Don't let humidity swing wildly between day and night.

Prevention

• Mag Cal with every feed in coco, soft or RO water.
• pH in range.
• Steady humidity and watering.

Monkey products that can help

Mag Cal

Magnesium and calcium supplement for coco and soft or RO water; calcium builds strong cell walls.

1 ml per litre (10 ml per 10 L), for coco and for soft or RO water.

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Stress

Monkey say mono-silicic acid helps carry heavy, immobile minerals such as calcium, aiding calcium absorption. Can help, alongside correct pH and Mag Cal.

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

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

When to get help

If new growth stays twisted and spotted after a week with pH, humidity and Mag Cal right, email info@monkeynutrients.co.uk with photos, your water type and medium.

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