Do you use Cal Mag during flower?

I’ve just come from the thread and heard someone say not to use Cal Mag during the flowering ?

I always use it otherwise my leaves turn yellow and eventually fall off !?

I’m curious to get this question out there and let’s talk about it ?!

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I follow along as I am about to put the girls into flowering

I hope so because I’m using it. Also, the bottle says it’s okay. I have a calcium deficiency at the moment so I’m forced to use it right now.

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It greatly depends on the nutrients you are using since Calmag usually is Calcium Nitrate that means has substantial N in it 4-0-0 for some 1-0-0 for other Cal supplements if you were using a N rich formula as a base like many Micro products you would steer clear of 4-0-0 as it would increase N
Some product lines like GH have 1-0-0 Cal mag which would be fine for use for first 3-4 weeks of flower during stretch and initial bloom but in soil much of what you use remains stored in media and degrading perilite will naturally release Cal over time since it is important for nutrient transport and structure it is never entirely removed but most micro B in 2 part systems have lots and your plant is no longer producing foliage or stems so only trace amounts are needed for mobility.
It’s addition during flower can be summed up as using 1 thing means less I can add of another since ppm only allows for so much at anytime without burn which is non reversible and has tragic effects in flower. Also knowing that the majority of plants growth has ended (not supporting new foliage) it’s demands are far less meaning it builds up in soil and plays havoc with ph if your ladies do not want or use it. [quote=“Paranorman, post:1, topic:8967”]
I always use it otherwise my leaves turn yellow and eventually fall off !?

that is caused mostly by the decreased N and your plant canabalizing to get more Macro nutrients but if using Cal helps by all means I am only voicing what I have found works for me. I cut Cal mag out once stretch is done with no ill effect of note get less tip burn and easier flush


@Donaldj Smart answer my friend…

Leaves also turn yellow due to 2 other processes I have typed it before let me see if I can find it, I learned that thanks to @Dumme


3rd reason lack of nutrients as mentioned above, otherwise @Paranorman, @Donaldj gave you a great answer

@Donaldj great answer and thanks for the explanation, I was a little surprised when I saw you say that in that other thread that’s why I came right here because I didn’t want to blow his post-up but would still like to hear more input on this ?

I use it til maybe the last three weeks or four weeks, then stop and let the plant do its thing and finish up (but I’ve quit Flushing them), but I use it right through the stretch and at least the first 4-5 weeks of flower altogether

I’m wondering if and how others use it ?

I also I noticed some is 1-0-0 and others are 2-0-0 …is the 2-0-0 stronger & better ?

I would assume the opposite since N-P-K 2-0-0 meaning lots of N still I use GH Cali-Magic 1-0-0 Calcium is the goal not N


I just noticed that today on botanicare brand, it was 2-0-0 instead of 1-0-0, I too use the GH Cal Mag product

Now that I’ve stopped flushing I use Cal Mag right through the whole grow, I was incorrect above that I stopped for the last few weeks (I often put one or two milliliters in my plain pH waterings, more if the plant shows any signs of deficiency)

I’m curious what others do regarding Cal Mag supplementation in flower ?

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I added 4ml/gallon for my watering today. 22 days into flower.


I have been useing it in flower I think I saw the same thread @Paranorman
I will stop feeding my plants about 2 weeks before harvest anyway so it should use up whatever nutes are stored
And I’ve been told it fine to use in flower as well


I use General Hydroponics nutes and follow the feeding schedule which recommends using Cal Mag during flowering.

Keep in mind: I feed only half recommended nutes, I feed every other week, end all nutes 2 wks before harvest.


So in flowering Cal is the goal?

I suppose my quote was vague since it was a reply? what I meant to say is you add a Calcium supplement for calcium not with the goal being to add more N
Products can vary and are marked with an NPK so if you are looking to add Cal during flower add product with a low N

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Thankyou @Donaldj, i have another question. This is prob going to sound stupid but is it ok to use nutrients that are for hydro in soil?

Indeed it is matter of fact most nutrient lines are created with both in mind and not all soils are actually soil :wink: Many are actually what is classed soil less Promix, Sunshine mix #4 most products consisting primarily of peat or smagnum SP? too early for me to spell Moss are classed as soil less. The major difference in product use is it’s ph when used in hydro which is adjusted to be lower than in soil

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I’ve heard that switching to from Calcium-Magnesium to Magnesium-Sulfur at mid flower is best since she always wants the Mag and needs the Sulfur for budding.


I just got this the other day, I do have a question about it tho, on my Nute schedule I am using General Organics Go Box, ran out of cal mag that came in the Go Box, Bought the Cali Magic not knowing it wasn’t what I was using, I read the back of the bottle and it says 1tsp per gal, but my schedule on the GO Box says for week 4 transition, 5ml per gal, which one do I listen to? I would like to add it to my water when I am not giving nutes.