Canna - CaO 12% Calcium

A single-element calcium fertiliser with 12% calcium oxide, for use in both vegetative growth and flowering. Made for growers who want to steer calcium on its own rather than through a blend.

Calcium appears on almost everything else's warning label

Set the mixing instructions for this whole CANNA range side by side and something stands out. The magnesium must not meet calcium. The phosphorus must not meet calcium. The potassium must not meet calcium. The Trace Mix must not meet calcium. And this product itself must not meet phosphate- or sulphate-bearing fertilisers.

Four of the other six bottles name calcium explicitly. Not because calcium is fragile, but because in concentrated form it reacts with phosphate and with sulphate, and most of this shelf is one or the other. What you get is a precipitate: a white sludge that will not redissolve and that you get to clean out of your jug or your lines.

The rule that follows is short and has no exceptions. Never let two concentrates meet directly. Add each product separately to a reservoir that is already full of water, and stir between additions. Diluted there is no problem at all; it is only the undiluted meeting that goes wrong.

What you are buying when you buy singly

A ready-made Cal-Mag has already solved this for you: the manufacturer picked forms that coexist and fixed the ratio between calcium and magnesium.

Buying singly hands that ratio back to you. If you see only calcium symptoms and your magnesium is fine, you can correct exactly that without pushing in magnesium you did not need. On a tight schedule, on RO water, or when acting on a leaf analysis, that is the difference between correcting and guessing.

What it costs you is the mixing discipline above, and that discipline lapses the moment somebody else makes up the reservoir. Weigh that in.

Where a calcium deficiency shows

Calcium barely moves within the plant. It travels upward with the water stream and gets locked into cell walls where it arrives, and it is not relocated afterwards.

So calcium symptoms appear in the youngest tissue: new leaf tips, growing points, young fruit. Old leaf carries on looking untouched even when the shortage has run for weeks. Correct it and existing damage does not repair; only what grows afterwards comes right. That makes calcium an element to stay ahead of rather than repair after the fact.

Technical Specifications:

• Type: single-element mineral fertiliser, liquid
• Manufacturer: CANNA
• Content: 12% calcium oxide (CaO), as stated on the label
• Mind the unit: 12% CaO is not the same as 12% calcium; as the element it works out at roughly 8.6% Ca
• Phase: vegetative and flowering
• Substrate: soil, coco and all hydroponic systems
• Mixing: do not mix in concentrated form with phosphate- or sulphate-bearing fertilisers
• Volume: 1 litre
• Packaging: 100% recyclable polyethylene, free of PVC and cadmium

Frequently asked questions

Why can this not go in with my other concentrates?
Concentrated calcium reacts with phosphate and with sulphate to form a precipitate that will not redissolve. Diluted it is fine: add everything separately to a full reservoir and stir in between.

Is 12% CaO the same as 12% calcium?
No. CaO is the oxide form. 12% CaO is equivalent to roughly 8.6% calcium as the element. Watch for that when comparing brands.

Why buy this instead of a Cal-Mag?
To set the ratio yourself. If you only need calcium, a blend also adds magnesium you did not ask for.

My old leaf is not recovering, is the dose wrong?
Probably not. Calcium is not relocated within the plant, so existing damage does not repair. Judge it on the new growth.

Where do I see a deficiency first?
In the youngest tissue: new leaf tips and growing points. Old leaf keeps looking fine.