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Thread: Phosphorus deficency. Advice?

  1. #1

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    Default Phosphorus deficency. Advice?

    Hi guys.

    My first grow has been going well up until this point. I started seeing some dark spots on the leaves and reddish leaf stems. After some digging my conclusion is that the plant has some P deficency.

    Also, I'm using a crappy PH soil meter that a month ago was reading 6.0 to 6.5 and now I'm seeing 5. Watered only using distilled water and got another batch of it 2 weeks ago.
    Regarding the watering part, what I think I may have done is water the plants a bit too early, not letting the first inches of soil dry up.

    I grow in Coco using ~30% perlite and use Biobizz nutrients.
    I'll put some pics down below.

    Any advice on how to deal with this?

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    Last edited by muffin_s; 25-11-20 at 04:21 PM.

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  3. #2

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    The few spots that I see look more like calcium deficiency and I wouldn't classify anything you have as being red stems. It doesn't hurt to feed more phosphorus at this stage since you are in flower, If you're bloom has some nitrogen in it I would be careful there. Your plants don't look nitrogen toxic, but they could turn that way real quick.



    J

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  5. #3

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    The bloom nutrient that i use has NPK 274, putting in 3-4ml per liter at this stage.
    Was thinking to feed her using higher PH water and see what the readings say.

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    I always like to let my pH drift between 5.8 and 6.2 or 3. You can probably go up to a feed level of EC 1.2 if you want. I would work up slowly if you do.



    J


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    EC was one of the characteristics I didn't take into account. Having no way of measuring that atm and considering the fact that I use distilled water, I presume that the EC of the water that the plants get is close to 0.
    Should I consider using some Calmag suppliment?

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  11. #6

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    Quote Originally Posted by muffin_s View Post
    EC was one of the characteristics I didn't take into account. Having no way of measuring that atm and considering the fact that I use distilled water, I presume that the EC of the water that the plants get is close to 0.
    Should I consider using some Calmag suppliment?
    You probably are going to need to use it, once in a while during veg and Early flower and possibly daily during late flower.



    J


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    The problem with the cal mag supplements is they tend to have quite a bit of nitrogen so you have to reduce whatever nitrogen sources you have if you want to use it regularly. I think most guys in your situation would be just fine with 1 ml per 4 l of mix.



    J


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    Thanks for the detailed explanations, Jingo! They surely are helpful.
    Will look to get some Calmag for the cuties and cut down the Nitrogen sources.

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    I see that a shop near me has some Canna Mono Calcium available. Do you think that would do the trick?

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  19. #10

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    Quote Originally Posted by muffin_s View Post
    I see that a shop near me has some Canna Mono Calcium available. Do you think that would do the trick?
    Never used it, it should have magnesium to be a complete balanced feed and the lowest nitrogen you can get. Usually that comes out to about 1 N, with good supplements some are quite a bit higher.



    J


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