CAL-MAG · Calcium · magnesium
Stop the spots.
Rusty spots, curled tips, pale new growth — classic calcium and magnesium hunger in soil, coco and hydro. CAL-MAG corrects it and keeps cell walls and chlorophyll where they should be.
Australian-made · 26 years in the US · N-P-K 5.2–0–0 · Ca 5% · Mg 1.4%
Why it matters
The most common deficiency.
Soft water and hard LED light both pull calcium and magnesium down fast in any medium. Left short, the plant stalls and marks up. Cal-Mag keeps it topped up.
Calcium
Builds strong cell walls — the plant’s structure and transport.
Magnesium
The core of chlorophyll — green leaves and photosynthesis.
Clean new growth
Heads off tip burn, spotting and pale tops before they start.
What’s in the bottle
Four minerals, big jobs.
Here’s what’s actually in it — read straight off the current bottle — and what each part does.
Calcium nitrate Mineral salt
Calcium plus nitrate nitrogen — builds firm cell walls and supports nutrient transport through the plant.
calciumcell walls
Magnesium nitrate Mineral salt
Magnesium plus nitrate nitrogen — the central atom of chlorophyll, driving photosynthesis.
magnesiumchlorophyll
Iron DTPA DTPA-chelated iron
A stable iron chelate (to roughly pH 7) declared on the label alongside the calcium and magnesium.
ironchelate
Zinc EDTA EDTA-chelated zinc
A chelated zinc source rounding out the label’s micronutrient support.
zincchelate
Why growers run it
Skip it vs. run it.
No Cal-Mag
✗
Soft water runs short fast.
✗
Rust spots and curled tips show up.
✗
New growth goes pale and slow.
✗
You’re always chasing the problem.
With CAL-MAG
✓
Calcium and magnesium kept topped up.
✓
Clean leaves, no spotting.
✓
Strong, green new growth.
✓
Prevented, not chased.
A little goes a long way
1 L → 1,000 L
of finished feed at 1 ml/L — cheap insurance against the most common deficiency in the tent.
Proof — label & MSDS
Straight off the label.
N – P – K
5.2 · 0 · 0
Type
Calcium magnesium supplement
Dose
1 ml/L
Made in
Australia
Ca + Mg nitrate + Fe DTPA + Zn EDTA
100% biodegradable
pH 8–10
By Agricultural Organics, South Australia
N-P-K 5.2-0-0 (all nitrate nitrogen), calcium 5%, magnesium 1.4%, iron 0.5% (DTPA), zinc 0.036% (EDTA), from the product label. Works in soil, coco and hydro. Composition and properties from the manufacturer MSDS.
When to use it
Weekly. Soil, coco or hydro.
Seedling
Veg
Flower
Late flower
Flush
Soil, coco or hydro, weekly1 ml/L
Soft water especiallyweekly
At first sign of spottingas needed
Stop the spots.
Keep it green.
Shop CAL-MAG →
Or DM FEED CHART to @bloom_crew_nate for your full feed schedule.
Images on this page are a mix of real photos and AI-generated illustrations, used to show how things work.