Calcium and magnesium are easy to overlook. Calcium builds strong cell walls and is tied to problems like blossom end rot, and magnesium sits at the center of chlorophyll, so a shortage shows up as yellowing between leaf veins. CALiMAGic from General Hydroponics adds both, and I am testing it alongside my coco coir trials.
What I’m testing
- Coco coir: coco tends to hold onto calcium and magnesium, so I want to see if supplementing makes a visible difference.
- Tomatoes: whether it helps container tomatoes in grow bags where watering can be uneven.
- Hydroponics: how it fits into a simple hydroponic setup using filtered water.
- Dosing: what rate plants actually need, starting low and staying at or under the label.
How I’m using it
- Shake well and measure carefully. A little goes a long way.
- Add it to the water first, before other nutrients, and stir.
- For hydroponics, check pH after mixing since supplements can shift it.
- Watch new growth for changes, since calcium issues show up on the newest leaves and fruit.
Results so far
Testing is in progress. I will update this page with what I see over a full growing cycle. Until then, treat these as my setup notes, not a final verdict.
Who it is for
Coco coir growers, hydroponic gardeners, people using reverse osmosis or very soft water, and anyone fighting a confirmed calcium or magnesium deficiency.
Common questions
What is Cal-Mag used for?
Cal-Mag supplements add calcium and magnesium. They are common in coco coir and hydroponic setups, and when using reverse osmosis or soft water that lacks minerals.
Does Cal-Mag prevent blossom end rot?
Blossom end rot is linked to calcium not reaching the fruit, which is most often caused by uneven watering. Cal-Mag can help when calcium is truly lacking, but consistent watering matters most.
Can I use CALiMAGic in soil?
Yes, at the label rate. Many gardeners use it in containers when plants show signs of calcium or magnesium deficiency.
Want to test it alongside me?
Prices and availability change often, so check the current listing on Amazon.
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