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Thread: What am I looking at? pH? P&K def?

  1. #1

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    Default What am I looking at? pH? P&K def?

    Hi guys, any advice appreciated.

    I've had signs of nute burn for a long time on this girl and after feeding last night I noticed almost immediately the leaf tips were getting worse, so I decided to flush out some of the feed with plain water about an hour after feeding. Not sure if that was a good or a bad move but it's done anyway. Today, as well as the burnt tips I've got a bunch of dark patches that look kind of like necrosis and kind of like the plant's been sprayed with something, although I'm fully confident it's not got splashed that high up during feeding.

    The pH seems to be too high for some reason and the symptoms look a bit like pH flux? They also, if you take into account the reddened stems and petioles and tips, look like a combination of P&K deficiency to my eye?

    thumbnail (61).jpgthumbnail (63).jpgthumbnail (64).jpgthumbnail (65).jpg

    Soil or hydro or coco: Soil

    Strain: RQS Quick One, a bit stunty from previous issues

    Photo or Auto: Auto

    plant age: 8 weeks

    pot size: 7l

    has it been repotted? and when?: never

    soil type: plagron lightmix/batmix

    nutes or additives used and how often for soil: Plagron alga bloom, 1/4 strength and green sensation 1/2 strength. I've been feeding every watering since it's only taking water every 3/4 days

    Air temps (max min): recently 22C-27C

    Res temps (max min): n/a

    humidity: Higher than I would like, varying between 50-60%

    lighting type and wattage (hps, led, cfl): LED LM301B strips, only 20W but dimmed in response to light stress

    Light schedule: 20/4

    ph level: This might be a problem, the runoff water last night measured at 7.0

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  3. #2

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    pH 7 isn't that high in flower and shouldn't be locking out p n k.

    Is it under fed? I dunno

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    soil p.h buffers to 7 that's totally normal


    how much is it drinking in 4 days?
    is the pot actually dry before you water?




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    Quote Originally Posted by Ben.g View Post
    pH 7 isn't that high in flower and shouldn't be locking out p n k.

    Is it under fed? I dunno
    Thanks for dropping in mate. It's possible it's under feeding and I'm misinterpreting the singed tips as nute burn when it's actually a K deficiency. Odd that it would spike after a feed if so but I guess it's always possible that I'm seeing things. She's a lot worse than yesterday so clearly the straight water hasn't helped. I think I'll have to up the feed and see how she responds to that?

    Quote Originally Posted by MonsterEnergy View Post
    soil p.h buffers to 7 that's totally normal


    how much is it drinking in 4 days?
    is the pot actually dry before you water?

    Thanks man. Weird, I think of soil as being pH 6.3-6.5, maybe I need to go back to the books! She's drinking roughly 1l each time, I'm waiting until the top almost an inch of the soil is bone dry, though it does seem to drain very slowly this soil so it's possible that's still too often. Shopping list for next grow definitely includes a bag of perlite!

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    Im sure i read somewhere before on here but ive noticed with my last 3 grows under LED as well that Ive had cal-mag issues, usually in late veg.(might just be coincidence?) They can go pretty pale like their not getting enough nitrogen,so naturally i added pm grow which led to burnt tips but after a few doses of cal-mag it seemed to sort itself out and had no further problems.

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    they need cal/mg more in flower than veg though ''soil growers'' that doesn't include anyone who has soft water or hydro
    the leaf tip burn is very minimal, you took them to peek feeding - that's a good thing

    cal/mg shows threw lower leaves turning yellow between the veins

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    Quote Originally Posted by Kurdt View Post
    Im sure i read somewhere before on here but ive noticed with my last 3 grows under LED as well that Ive had cal-mag issues, usually in late veg.(might just be coincidence?) They can go pretty pale like their not getting enough nitrogen,so naturally i added pm grow which led to burnt tips but after a few doses of cal-mag it seemed to sort itself out and had no further problems.
    Probably something else I need to think more about next time, I've been using epsom this grow but might get a full cal/mag for next time.

    I'm sort of inclined to give her a booster feed tonight, maybe a bottom feed with bloom nutes, any thoughts?

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    Give the feeding a shot Rebel. If plain water hasn't helped.

    Just when I saw the half strength nutes made me think, I'm sure (although don't quote me) that plagron light mix only has enough feed for around 2 weeks.

    Hope it works out for you, keep us updated

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    Quote Originally Posted by thelastrebel View Post
    Thanks man. Weird, I think of soil as being pH 6.3-6.5, maybe I need to go back to the books! She's drinking roughly 1l each time, I'm waiting until the top almost an inch of the soil is bone dry, though it does seem to drain very slowly this soil so it's possible that's still too often. Shopping list for next grow definitely includes a bag of perlite!


    should have said any good soil will buffer to 7 ph

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    Quote Originally Posted by Ben.g View Post
    Give the feeding a shot Rebel. If plain water hasn't helped.

    Just when I saw the half strength nutes made me think, I'm sure (although don't quote me) that plagron light mix only has enough feed for around 2 weeks.

    Hope it works out for you, keep us updated
    Thanks fella, I'll give it a go, bottom feeding so as not to suffocate the top of the soil too much hopefully. I'd been keeping nutes light due to the constant singed tips I've had but the more K def pics I look at, the more I think I've transitioned from nute burn to K def without spotting the difference.

    Half the soil is lightmix half is batmix, which by all accounts is hot enough to reboot the sun, but even then it can't last forever!

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    I would pin that down to overwatering imho .

    Plant looks droopy and P def and all sorts of other can occure because of overwatering wich seems to be case here . Your soil in the background looks soaked .

    Do you let pot get light before feeding/watering ?







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    Quote Originally Posted by Trex View Post
    I would pin that down to overwatering imho .

    Plant looks droopy and P def and all sorts of other can occure because of overwatering wich seems to be case here . Your soil in the background looks soaked .

    Do you let pot get light before feeding/watering ?







    Sent from my SM-G950W using Tapatalk
    Thanks man.

    Overwatering would explain a lot, I've recently started growing some garden herbs in the same soil and I've been surprised by how long those 400ml pots stay wet for. Having not grown weed before (or anything really indoors) there's an element of guess work as to how long it should go without but it the soil does retain that much moisture then maybe it does need to be longer.

    Since the feed top up earlier, which I do think was probably worthwhile, I'll use the old school towel method to wick some moisture theough a bit faster and I'll see about leavibg it longer before watering next time. Trying to go by weight is again tricky on a first run - a suggestion I was given a while ago was to have a similar size pot of just dry soil nearby to use for comparison purposes and I'll have to start doing that I think.

    Thanks for the input man, much appreciated.

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