Calcium Deficiency in Cannabis: Signs, Causes and Fixes

Calcium Deficiency in Cannabis: Signs, Causes and Fixes
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Calcium helps cannabis plants build strong cell walls, healthy roots and sturdy stems. When plants don’t get enough, growth suffers quickly. If you want to catch the problem early, read our guide to [early calcium deficiency in cannabis](https://kushstation.co/tag/early-calcium-deficiency-cannabis/).

[https://kushstation.co/tag/early-calcium-deficiency-cannabis/](https://kushstation.co/tag/early-calcium-deficiency-cannabis/)

### Signs to Watch For

Calcium doesn’t move easily within the plant, so symptoms usually show up on new growth first:

*   Small brown or rust-coloured spots on leaves
*   Curled, twisted or distorted new leaves
*   Weak, brittle stems
*   Slow growth and underdeveloped buds

### Common Causes

Often the problem isn’t a lack of calcium but the plant’s inability to absorb it. The usual causes are:

*   **Incorrect pH:** Keep soil at 6.0–7.0 and hydro at 5.5–6.5.
*   **Soft or RO water:** It contains little or no calcium.
*   **Nutrient imbalance:** Too much potassium or magnesium can block calcium uptake.
*   **Overwatering:** It damages roots and reduces absorption.

### How to Fix It

Check and adjust your pH first. Then add a Cal-Mag supplement, or mix dolomite lime into soil for a slow-release source. If you suspect nutrient buildup, flush the medium with pH-balanced water. Damaged leaves won’t recover, but healthy new growth should appear within a week or two.