cal mag

Discussion in 'General Marijuana Growing' started by tom mix, Aug 12, 2017.

    tom mix

    tom mix Well-Known Member

    do i have to use cal mag, useing happy frog,botanicare pro grow and pro bloom

    TacoMac Well-Known Member


    Are you growing in soil? If yes, then you do NOT need cal mag. You need lime. It's 5 bucks a bag. Add about 8 to 10 tablespoons in each plants pot when you mix the soil and you're good to go.

    Are you hydroponics? Then yes, you will need it. No exceptions.

    growin-Jables Well-Known Member

    Why isnt cal mag needed when growing in soil?

    SoOLED Well-Known Member


    - high porosity hydro mediums have zero nutrients.

    - organic soil/compost fillers are meant to meet nutrient needs for each phase of the cycle. (there are many variants in soil use)
    too larry

    too larry Well-Known Member

    I do my own soil mixes with lots of goodies, but I still add Epsom salts to my water during the grow. Especially in flower.

    2 tbs per 5 gallons of water.
    Last edited: Aug 12, 2017
    Jimmy Verde likes this.

    growin-Jables Well-Known Member

    What after 4 weeks once the nutrients are depleted ?

    SoOLED Well-Known Member

    I don't use soils or compost, there are people here who have lots of experience working like that.

    I bet if you search for threads on soil mixes you will find a lot of data.

    growin-Jables Well-Known Member

    From what I researched and was informed by the gentlemen at our local hydro store, pre mixed " organic" soils like Fox Farms Ocean Forrest has readily available nutrients that will prevent needing any other added nutes for a duration of 4 weeks. After that, all the nutrients have been absorbed and depleted. So since most plant cycles are anywhere between 10 - 14 weeks. I would say Cal Mag is absolutely necessary once those 4 weeks have expired.

    TacoMac Well-Known Member

    The layman's answer is: Soil contains and holds nutrients naturally. In fact, there's calcium already in it. When you add the lime, it contains BOATLOADS of calcium and some magnesium that will break down in the soil as you water as time goes by, so the soil will never be short of calcium, so you don't need cal mag. In a worst case scenario, you might have to water once with a half teaspoon of Epson salts to add some magnesium, but that's about it and it rarely happens.

    Hydropnic grows have no medium that holds on to any nutrients at all. The roots given only those nutrients that are in the solution. The typical solutions are never going to have enough calcium in them, and magnesium is also iffy. So a cal mag regimine becomes necessary due to the fact that there is always a need for calcium and magnesium over the plants life and the standard nutrients do not contain nearly enough of either.

    That's why cal mag was made to begin with. Yes, it's expensive. Hydroponics are very expensive...about 25 times more expensive than soil grows. If you can't afford it, don't do it. It's that simple.

    I grow for only my personal use and found that hydroponics simply aren't worth it at all. On a larger scale, yes. It makes a hell of a difference. But if you're only doing two plants for your own use and maybe a friend or two, you're wasting your money even bothering with hydroponics.
    papa canna

    papa canna Well-Known Member

    If you are using bagged soil, and TAP WATER it is unlikely that you will ever see calmag deficiency. A lot of people do not understand calmag. They hear about it a lot, so they add it religiously.

    But most of the old school experienced guys around here will tell you, not only do you not need it in soil with tap water, but those bottles can do more harm than good if you are not careful
    TacoMac likes this.

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