Cal Mag Feeding

Should I be using some type of cal mag with
My feedings. Was wondering what the growers here are doing and what product they recommend

I used some on both my dirt grow and my areponics grow and they both loved it. I just added 1ml with your favorite nutes. My brand is Sensi Cal. 4-0-0 but I dont think the brand matters. It will raise your PPM 80-90 points.

Happy Growing


I use cal mag with my feedings normally.
I use a organic dry fertilizer by vermicrop organics and water it in with photosynthesis plus. I usualy add cal mag into the mix every other feeding sometimes every feeding depending on the age.
I use the cal mag supliment because my base nutrients don’t have much in it.
I would say it would depend on what nutrient line you use. I’ve heard the flower power nutes don’t need it because it already has enough in it.

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@Jmesser80 @MAXHeadRoom, thx for input folks… I’m using ff trio but have never used any cal mag in any feedings… So is it something I should be thinking about adding to my feedings? I’m in soil, ffof… Plants seem fine but thought I should buy some to have on hand


I started using it because one of my plants was turning purple in the aeroponics grow and I saw such a positive response to it that I included it in my dirt grow too.


I’ve never used fox farm so I’m not sure if that line has some in it already. It wouldn’t hurt to have some in hand. I know there are a bunch of members who use fox farms hopefully one of them can shed some more light on it for you.


Most quality Base nutrient systems contain enough Calcium and Magnesium that Cal Mag is not needed unless you are using some custom formula like the “Lucas” method, or have a defined deficiency. Plants only uptake what they need and unless you have a deficiency, you don’t apply CalMag.

IN any soil look for dolomitic lime. If you find it, then you do not need to add CalMag to the soil. Even after the soil nutrients are depleted, you would be adding a base nutrient, and still would not need CalMag.

IN closing; You can add extra CalMag if you want but the plant only takes up the amount of Calcium and Magnesium it needs and any excess is a waste.

IN base nutrients Calcium is generally defined under Calcium Nitrate, and the 4-0-0 npk ratio one of you described proves this fact. What we might take from this is; We definitely do not want to add any 4-0-0 during flower photo period.

Happy growing. :slight_smile: lw


Thx @latewood… I’m new and would rather not add anything… I’m using ff trio but maybe half strength… Going slow and learning… I wasn’t sure if in flower, cannabis may need extra nutes besides the ff trio… Thx for the explanation and also thx to other posters for their thoughts

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If you are using Foxfarm Grow Big, Big Bloom, Tiger Bloom, then you add the recommended dosage. 1/2 strength does not protect your plants (taking it easy…), 1/2 strength leads to nutrient deficiencies. Think about it. This company spends millions to develop a product used by millions…probably, and some growers dismiss their instructions.

You can use The trio all by itself, without a doubt. IN fact; The best way to learn in the beginning is to use a stand alone base nutrient for the 1st couple of grows, and then maybe add a flower booster and other beneficial additives later, after you learn how the plant reacts, and you learn to grow.

Keep in mind. Grow Big is used alone. 1 TBS. per gallon

Big Bloom is combined with Tiger Bloom. Follow the nutrient schedule provided by FF to guage your application of this combination in the flower phase. I will help you down the road if you are second guessing yourself.

If you are using Foxfarm soil. Do not use nutrients until 4-6 weeks into grow when you notice the plants want something more. This is because they have depleted beneficial minerals from the soil mix and need to be supported by the liquid nutrients. :slight_smile:


@latewood, ok so I should be using full strength as per schedule? I’ve been reading so many posts that say go slow with nutes to avoid nute burn etc… What I have been doing the last 2 times I fed nutes is mixing all 3 in a gallon of distilled water… My next feeding is week 6 which calls for 3 tsps of big bloom, grow big and tiger bloom(if I remember correctly) what I did last time for week 5 was gave 2 tsps I big bloom and grow big and 1 tsp of tiger bloom… All mixed together in one gallon… Am I doing this correctly?

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No. Not IMO.

In veg, I only use Grow Big. 1 TBS. per Gallon

IN Bloom, I think it was 1 TBS per gallon Big Bloom, and 1 -2 tsp. of Tiger Bloom. Big Bloom does not raise the PPM/EC much. It is the addition of Tiger Bloom 1-2 tsp per gallon (1 tsp for 1st part of flower), that raises the ppm into the desired range

I do not know what you are growing in, or how old your plants are.

Long story short, I have 2 northern lights (not from ILGM ) fem photos, they sprouted April 9… Changes the lights schedule from 18/6 to 14/10 and they started to flower… I’ve never grown before so really didn’t know the flowers that were starting was plant budding, I thought they were pre flowers… Lol… They are in ffof soil and previous to them budding, I never gave them any nutes… So when I changed lights on may 8… It was like another 2 weeks or so when I have them the week 5 ff trio dose but this technically was their first feed… My grow kin of went sideways on me lol

Next water them with PH 6.5 water. Next feeding. Give them 1 TBS. of Big Bloom and 1 tsp. of Tiger Bloom. Once a week you give them the nutes and PH’d water in between. This allows the plant to uptake what it needs, and you are constantly flushing unused slat buildup from your medium.


@latewood, also on my ff trio schedule, I don’t see any tablespoon dose? Only teaspoon dosage, I posted latest pics from Sunday

PLant looks great. Do you have TDS or EC meter? If so; Make sure you get ppm level between 1000-1200 ppm.

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So no grow big? @latewood

I do not see any point. The Big Bloom and Tiger Bloom have nitrogen,and adding those 2 parts should bring you up to a nice ppm range 1000-1200 ppm

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Yes I have ppm meter, usually mix nutes up, ph water then take ppm reading… Water plants and then take runoff, measure ph and ppm of runoff… Make notes in my journal each time I feed @latewood


I see what you mean… Sounds good @latewood, thx for input

You start with a TBS. of Big Bloom. Measure your ppm or EC, and then add Tigetr Bloom until you get into the range mentioned. After more buds form, you can strengthen the formula a couple hundred ppm if you want to.