Nutrient IssuesSerious
Calcium Deficiency in Cannabis
Calcium deficiency is extremely common in coco coir grows and when using RO or filtered water. It shows up as small rust-colored spots and distorted new growth.
What it looks like
- ●Small rust-colored or dark-brown spots on young leaves
- ●New growth may look twisted or distorted
- ●Hooking leaf tips or necrotic spots
- ●Common in the upper part of the plant (calcium is immobile)
Quick diagnostic checks
1Coco + RO water? Add Cal-Mag TODAY — it's not optional
2If spots appear, dose a heavier Cal-Mag and check pH
Causes ranked by likelihood
1. Not enough calcium in water/feed
Most commonSigns
- ●Using RO, distilled, or filtered water
- ●Growing in coco coir
- ●Not using Cal-Mag supplement
Fix
- ✓Add Cal-Mag at 3-5 ml/gal every feeding
- ✓Coco + RO water ALWAYS needs Cal-Mag — mandatory
Recommended products
Botanicare Cal-Mag Plus
Essential for coco and RO setups
2. pH too low for calcium uptake
CommonSigns
- ●Runoff pH below 6.0 in soil
- ●Calcium is in feed but not absorbing
Fix
- ✓Raise water pH to 6.3-6.5 (soil) or 5.8-6.2 (coco)
- ✓Use pH Up to adjust
⚠️When to worry
Cal deficiency during flower can cause bud defects and lower yield. Fix promptly.
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