Can you confirm if this is mag deficiency?

Discussion in 'Marijuana Plant Problems' started by noobgrowr, Aug 20, 2017.


    noobgrowr Well-Known Member

    20170820_004852.jpg 20170819_234538.jpg 20170820_004852.jpg 20170820_004912.jpg 20170819_234538.jpg Title says it all. Can you confirm my belief that this is a magnesium deficiency? Had these clones for about a week and a half, they've grown very well and other than this they seem quite healthy. Started a few days ago, I've got 2 Kandy Kush, a Durban Poison, and a Cherry Lime Haze. This one is the CLH and it's definitely the healthiest and I believe that's why it's showing these signs so quickly. Started about 4 days ago with just some yellowing along the edges of one or two leaves, then a little brown spotting, and then a little more complete spotting like this. It's only on 2 or 3 leaves but it's a little bit on the other plants as well.

    Probably 3 weeks old
    20/4 light cycle
    300w (5w diode, red, white, and blue) LED and 7 100w CFLs along sides
    Black magic soil from home depot
    Black magic nutes A+B
    Neem oil
    Been struggling with ph, it's been right about 7 the whole time, trying to bring it down closer to 6-6.5.

    After my research it seems it's either magnesium or calcium or both. Logically I bought some Cal-Mag to remedy and ran a teaspoon in a half gallon and ran some through 2 days ago. Also mixed some in with some ph'd water in spray bottle and have been spraying the leaves of all plants multiple times per day. Roots are peeking out the bottom (all nice and white btw) and I'm going to be moving to 5 gallon tomorrow along with a ph'd, cal-mag'd and molasses flush.

    Oh also all stems are mostly purple with some streaks of green.

    Last edited: Aug 20, 2017
    Lucky Luke

    Lucky Luke Well-Known Member

    Looks hungry to me.
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    noobgrowr Well-Known Member

    For? I went with 1/4 strength for the first (and only) two feedings that I've done as they are pretty young. As I mentioned the roots are peeking out the bottom and I'll be transplanting tomorrow. I'm only doing that for the Durban and the CLH as they are both doing very well besides this issue. The Kandy Kush's on the other hand are a different story. They are being very finicky and not doing so hot. Getting over watering signs on the same watering schedule and amounts as the Durban and CLH and their dirt is still wet and dark on the surface as opposed to nice and dry on the Durban and CLH. I think I'll be stepping up feeding tomorrow for those two and I'm gonna really let the Kush's dry out before hitting them with a feeding+Cal-Mag. Should I just keep up with the Cal-Mag or what do you recommend Luke?
    Lucky Luke

    Lucky Luke Well-Known Member

    I'll let the more experienced growers give you the advice as im not familer with your nute brands etc.
    To me they just look hungry. They are light green and a little mottled. I agree on the cal/mag thing but id also say they are short on N.
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    SoOLED Well-Known Member

    berry-ummm...not the cereal.

    its likely more then one micro def.
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    noobgrowr Well-Known Member

    Can you expand on that a little? Berry? Barium? Lol I think they are hungry and will be stepping up the nutrient schedule with transplant tomorrow so hopefully that will help bring them back into balance. And again I'll work on bringing the ph back to 6.5 as it's running a little alkaline at 7-7.5

    noobgrowr Well-Known Member

    Thanks Luke hopefully I get some solid answers. More nitrogen because the new growth is kinda light green?
    Lucky Luke likes this.

    BobCajun Well-Known Member

    Mag deficiency doesn't cause dead spots, just yellowing between the veins. Looking at the Black Magic site I see that the ingredients only include the micros iron, cobalt and molybdenum. Maybe the soil or tapwater provides enough of the others, and maybe not. Here's the ingredients right here. Do you see zinc, copper, boron etc? You shouldn't need to add cal/mag though, since it has plenty. Can't really make out the numbers on the label image but I'm sure there's plenty of calcium at least, from the calcium nitrate. There may be the other mics on the label somewhere, I just can't read it. They purposely used a blurry image or something.

    Maybe Black Magic isn't the best brand of nutes around. I bought one brand once, NutriPlus, and found on the label that all they supplied for micros is molybdenum, nothing else. So even if you wanted to add a micro mix you're need one with no moly or very little or else they'd get a double dose. You gotta watch those labels. Also this page said Black Magic is a low end nute line that is now being sold as high end after Miracle Grow bought the brand like they did with GH. I think the GH line is good though. NutriPlus was cheap as hell, all because they didn't put the costly micros in there.

    Derived From:
    • Ammonium Nitrate
    • Potassium Nitrate
    • Calcium Nitrate
    • Cobalt Sulfate
    • Iron DTPA
    • Sodium Molybdate
    • Ammonium Phosphate
    • Monopotassium Phosphate
    • Magnesium Sulfate
    Last edited: Aug 20, 2017
    noobgrowr likes this.

    noobgrowr Well-Known Member

    Thanks Bob, so should I drop the Cal-Mag from the feedings? I'll keep using the Black Magic nutes since I already got em but I can pick up something else to add to the mix. What do you recommend I pick up?

    I'm in Colorado so there's plenty of hydro and grow stores around. Should I go talk to them and see what they recommend as well? Is this even that big of a deal or am I just being an overprotective plant parent?

    noobgrowr Well-Known Member

    Bob, here's ingredient pics from the soil mix and the two bottles of nutes

    Attached Files:


    im4satori Well-Known Member

    to me they look hungry

    several def happening

    magnesium def yes
    calcium def yes
    nitrogen def yes

    like @Lucky Luke said
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    im4satori Well-Known Member

    your fertilizer is organic so it wont/might not become available to the plant for some time after you add it

    calmag gives N and magnesium and calcium so itll help

    but make sure you understand the difference between an organic fertilizer and a water soluble fertilizer and how it works

    noobgrowr Well-Known Member

    Awesome! Thanks man. Any idea of another nute bottle I should pick up?

    BobCajun Well-Known Member

    I still can't see any micros aside from the iron, cobalt and moly. The growing mix looks pretty good though, so probably has some micros in it from the various guano type stuff in it. It'll probably grow out of it. I've seen a lot worse. For other nutrient brands, the GH stuff seems fine to me, like FloraNova and MaxiGro. I don't recommend the Bloom type, just the Grow type. Too much phosphorus in the Bloom. I just use the Grow in all stages myself.

    Another product I saw but haven't actually tried yet is Miracle Gro Shake & Feed Tomato, Fruits and Vegetable. It looks very complete. If it was a powder you could use it as a hydro nute, it's so complete and well balanced. It's slow release pellets. You would mix it into the medium. Hard to screw up that way, just put the recommended amount in and then just water with plain water after that, unless it doesn't seem to be working well enough. They have other Shake & Feed products but they don't have as good a mixture of nutes. That's the only kind I recommend, the tomato kind. It's 9-4-12, that's a pretty good ratio.
    Last edited: Aug 20, 2017
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    noobgrowr Well-Known Member

    I thought the slow release ones were bad? And trying to stay away from MG is a good idea?
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    im4satori Well-Known Member

    the GH floranova grow and bloom are top notch and a true all in 1 complete fertilizer
    has kelp, aminos, fulvic, and properly balanced and the directions are good
    full dose 7.5mls per gallon

    the maxi grow and maxi bloom are also good balanced fertilizers and more economical to buy
    Id prefer to use the maxi 50/50 grow/bloom for flower and just the grow for veg
    4 to 6 grams total per gallon for full strength

    so that's per gallon
    during veg
    4 to 6 grams maxi grow

    during bloom (50/50)
    2 to 3 grams maxi grow
    2 to 3 grams maxi bloom

    if you choose either of these you wont need or want to use another product, theyre already balanced as they are so theres no need for additional bloom boosters or silica products and youll likely/possibly not need the calmag but keep some around just in case

    also I d recommend keeping some Epsom salt around but youll likely not need it either

    (I wouldn't use MG unless I had no other choice)

    one more thing

    don't use calmag if you want magnesium... calmag is mostly calcium and then nitrogen and lastly it has a small amount of magnesium
    look at the % amounts on the bottle

    3.2% calcium
    1.2% magnesium

    if you want magnesium use Epsom salt ...1/4 to 1/2 tsp per gallon max
    if you want calcium use calmag 2 to 4mls per gallon max
    Last edited: Aug 20, 2017
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    polishpollack Well-Known Member

    Since the grower has said they've already given calmag, it's unlikely to be magnesium or calcium.

    noobgrowr Well-Known Member

    Satori, awesome info thanks so much. I'm going to look into the maxi line but tbh, for my first real grow I may just try and make this work with what I've got but I will check out my local store for that.

    I just transplanted the Cherry Lime Haze and the Durban Poison to 5 gallon buckets and the roots looked incredible. Bright white and wrapped all along the outside and bottom. They were just peeking out the bottom. I flushed them with some ph'd water at 6 to balance out the high ph soil prior to moving them into the big buckets. The two Kandy Kush's are looking really sad. Small leaves curling down and the bottom can ones yellow and bad. The new growth is small and pale green. I'll get some pics of those two and hopefully I can get some help on all of them in one fell swoop.

    I gave them Cal-Mag only once so far, a few days ago. Can't really tell if it's made a difference so far though.

    noobgrowr Well-Known Member

    Here's the two very sad Kandy Kushs, followed the CLH and the Durban. Waiting for the Durban to dry out but the CLH is nice and perky. Hopefully the spots clear up.

    Attached Files:


    noobgrowr Well-Known Member

    Welcome to suggestions for how to make these better lol especially those poor kush's. I was told they are very particular and hard to grow. Which I'm certainly seeing

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