Plant Magic - Magne-Cal+ - Calcium and Magnesium Deficiency Corrector
Best for: growers correcting a calcium or magnesium deficiency, or wanting to support potassium uptake alongside a PK booster.
Our thoughts
Cal-mag issues are one of the most common deficiencies growers run into, especially in coco or with soft water, and they're easy to spot once you know what to look for - interveinal yellowing on older leaves is the classic sign. Magne-Cal+ is a straightforward fix rather than a preventative "just in case" additive, so it's worth keeping on hand for when (not if) you spot the signs.
Plant Magic Magne-Cal+ supplies calcium and magnesium, the two secondary nutrients that sit alongside nitrogen, phosphorus and potassium in importance but often get overlooked until a deficiency shows up. It's formulated with calcium oxide (roughly 5.0%, giving around 3.6% elemental calcium) and magnesium oxide (roughly 2.5%, giving around 1.5% elemental magnesium), plus chelated iron and trace elements like zinc and molybdenum to support overall plant health.
It's used both as a corrective feed for crops already showing deficiency symptoms and as a supporting additive alongside a PK booster, since adequate calcium and magnesium levels help plants take up potassium more efficiently during the demanding bloom phase.
How it compares
Cal-mag correctors are a near-universal additive across growing media, especially in coco, where calcium and magnesium lockout is common.
- Compared with General Hydroponics CaliMagic, both are dedicated calcium-magnesium correctors used the same way, with brand and pack size being the main practical differences.
- Compared with Botanicare Cal-Mag Plus, which also includes iron, the two products serve the same corrective purpose with broadly similar supporting trace elements.
- Compared with relying on your base nutrient alone, a dedicated cal-mag additive gives you a faster, more targeted fix once you spot yellowing between the veins on older leaves.
This is a genuinely necessary product for most coco growers rather than an optional extra - worth having in the cupboard even before you need it.
Usage guidance
Magne-Cal+ can be used preventatively at a low dose or corrective dose once symptoms appear.
Preventative dosing
Add a small dose to your regular nutrient solution, particularly if you're growing in coco or with soft/RO water, where cal-mag lockout is more common.
Corrective dosing
If you spot interveinal yellowing on older leaves, increase the dose following the label rate until symptoms clear, then return to a maintenance level.
Alongside a PK booster
Run it together with your PK booster during bloom to support potassium uptake and reduce the risk of a secondary deficiency showing up.
Technical specifications
- Calcium: approx. 3.6% elemental (5.0% CaO)
- Magnesium: approx. 1.5% elemental (2.5% MgO)
- Total nitrogen: approx. 2.9%
- Chelated iron: approx. 0.04% (EDTA)
- Function: corrects calcium/magnesium deficiency, supports potassium uptake
- Suitable media: soil, coco, hydroponics
- Sizes available: 500ml, 1 litre, 5 litre and 10 litre
- Brand: Plant Magic
Who this is for
- Coco growers, where cal-mag lockout is especially common
- Growers on soft or reverse-osmosis water with little natural calcium or magnesium
- Anyone already seeing interveinal yellowing on older leaves
- Growers running a PK booster who want to support potassium uptake
Our take
Cal-mag deficiencies are common enough that this isn't really an optional extra for coco growers - it's closer to a standard part of the kit.
Does exactly what it should, day in, day out - worth having on the shelf before the yellowing shows up, not just after.
