Causes of deficiency
Calcium is a tricky nutrient .
No energy is needed for uptake - plants absorb calcium passively, as they take up water. It’s then moved up the plant via transpiration. If the humidity in your grow room’s not very high, and plants aren’t taking up and losing water through leaves, calcium deficiencies often occur.
If humidity is very low, and the stomata close to save water, then calcium will again become an issue. You really have to keep an eye on your growing environment.
Calcium deficiencies are most common in coco.For all its virtues, coco notoriously holds onto calcium (Ca) and in some instances nitrogen (N).
To make matters worse, coco also releases potassium (K). Too much of this can cause a calcium deficiency, since the two are chemically similar.
Don’t panic – just make sure you use a coco nutrient and CalMag.
Calcium deficiencies can also occur in hydroponic systems. Especially if you use soft or RO water with a general base nutrient. To prevent problems, use a soft water formula, which contains more calcium.
As with all nutrients, you can get a calcium deficiency by underfeeding or having the wrong nutrient ratio. Adding too much potassium and magnesium, and the presence of too much sodium will cause calcium issues.