IONIC Cal-Mag Pro by Growth Technology | Calcium Magnesium Iron Supplement

IONIC Cal-Mag Pro — The Nutrient Nobody Asked For, and Everybody Needed

Here is a peculiar fact about growing anything, in any medium, anywhere: the two elements your plants are most likely to run short of — calcium and magnesium — are the two nobody thinks to buy. Nitrogen gets all the glory. Phosphorus and potassium get their own flashy "Bloom Boost" branding and a picture of a very large tomato on the label. Calcium and magnesium just quietly run out, somewhere around week four, and nobody notices until the leaves start telling on you.

This is, if you think about it, a problem of framing rather than chemistry. A "Cal-Mag supplement" sounds like an optional extra — the horticultural equivalent of undercoating on a new car. IONIC Cal-Mag Pro, made by Growth Technology, is not that. It is closer to what a good structural engineer would call load-bearing. Remove it from a coco or hydro feeding regime and the whole thing doesn't collapse dramatically — it just quietly underperforms, which is somehow worse, because nobody can quite say why.

What Makes This Particular Cal-Mag Genuinely Different

Most Cal-Mag products are one idea wearing different labels: calcium nitrate, magnesium sulphate, done. IONIC Cal-Mag Pro is built from three separate calcium sources, including a chelated form designed for rapid uptake — the plant equivalent of skipping the queue rather than waiting in line. Alongside the calcium (5.6%) and magnesium (4.01%), it carries chelated iron, humic acids, and amino acids — ingredients that don't just correct a deficiency but help the plant actually do something useful with the correction once it's been made.

This is the detail most Cal-Mag products skip, and it's the detail that matters. A calcium deficiency isn't really a shortage of calcium; it's a shortage of calcium the plant can use in time. IONIC Cal-Mag Pro is formulated around that distinction.

🌿 What It Actually Fixes

• Slow, sluggish mid-season growth — the unglamorous stretch between a strong start and a strong finish, where most Cal-Mag deficiencies quietly take hold.

• Interveinal yellowing — the tell-tale striped look of a magnesium shortfall.

• Small, dark, sharp-edged spots on leaves — classic calcium deficiency, and a sign that's easy to miss until it isn't.

• General pale, tired foliage — often blamed on everything except the actual cause.

• Nutrient lockout in coco — coco coir binds calcium and magnesium more readily than soil or hydro, which is precisely why coco growers reach for this bottle more than anyone else.

How To Use It

To prevent deficiencies: add at 0.5ml per litre as part of your regular feed.
To correct an existing deficiency: increase to 1–2ml per litre until the plant recovers, then step back down.
Growing in coco? Pre-drench your medium with a Cal-Mag solution before potting on — mix at 1ml per litre, water the pot through until you see runoff, and plant the following day. It's a small step that prevents a much bigger one later.

Always shake well before use, check pH and EC after mixing, and add it to your reservoir after your base nutrients rather than in isolation — nutrients, like people, tend to behave better when introduced properly rather than all shouting at once.

Product Specifications

• Calcium (Ca): 5.6%

• Magnesium (Mg): 4.01%

• Iron (Fe): 0.15% (chelated)

• Also contains: amino acids, humic acids, complex organic plant extracts

• Suitable for: soil, coco, and all hydroponic systems including NFT and flood & drain

• Brand: IONIC, by Growth Technology

💉 Measuring Syringe available separately, for growers who'd rather measure 1ml properly than guess and hope — a surprisingly large source of feeding errors, and an entirely avoidable one.

Available in 300ml, 1 Litre, and 5 Litres, so whether you're running a single tent or a full room, there's a bottle sized for what you're actually doing rather than what the biggest pack happened to be.