How long does it take for CalMag to kick in?

My plants have a bad CalMag deficiency for a 2 weeks now Iv been giving them .5ml of CalMag per liter for 2 feedings. I have my plants in 10l pots and give them 2L per plant ever 2 day with a ph of 6.5-6.6.

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Cannabis will immediately begin absorbing it, but don’t expect damaged leaves to recover. What are you expecting to see when it “kicks in”?

Your plant also looks nitrogen deficient. Have you been feeding a balanced cannabis fertilizer? Do you know your runoff PPM?


Agree with @MidwestGuy and would add that 5ml per litter seems overkill assuming 5ml is recommended for a gallon (4 liters). It’s hard to over-dose calcium and magnesium but from what I’ve researched an excess can prevent other macro/micro nutrients from being absorbed :love_you_gesture:


I agree. This is probably one of the reasons that some grower’s answer to every problem is to “Give it more cal/mag.” Growers here don’t do that so much, but some of the other forums it is very common.

I used 5ml per gallon, but one gallon only, when I was using the FF Trio.

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Yep I see that a lot :love_you_gesture: