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Thread: First Grow - Help Needed in Identifying Problem(s) - Possible P/K Deficency?

  1. #1

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    Default First Grow - Help Needed in Identifying Problem(s) - Possible P/K Deficency?

    Hi all,

    First-time grower and first-time poster here.

    I’ve got a bit of a problem on my hands and am hoping some of you may be able to give me a bit of a steer.

    Here’s the details:


    Growing Medium: Soil
    Strain: Super Silver Haze
    Photo or Auto: Photo
    Plant age: 10
    Quantity: 5
    Indoor/Outdoor: Indoor on poor weather days and outdoor on good weather days (1-10 weeks) and outdoor (after 10 weeks) (I switched to fully outdoor because of some mold/mildew problems and plants outgrowing indoor growing area)
    Location: UK
    Nutrients: Vitalink Bat Guano (5-10 weeks); Formulex (after ten weeks; only one feed this morning)
    Light schedule: 16-8 (1-10 weeks); outdoors (after 10 weeks)


    They were coming along very nicely until about 5 weeks old. At this point the new growth became a lighter, lime green colour. As a first-time grower wary of over-watering and over-feeding, I held off with the nutrients as long as possible. I took this as my sign to start feeding with diluted guano. For the first 2-3 weeks of this feeding regime, they responded well and the new growth grew every-so-steadily darker (though never completely). Approximately 2 weeks ago (8 weeks since germination), though, the new growth started growing quite light again. Here they are two weeks ago (8 weeks after germination) when the new growth started turning lighter again.

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    At around the same time, I started getting some leaf septoria and mildew on a handful of leaves. I initially removed the affected leaves but once it spread to too many leaves (one week ago/9 weeks since germination) I give it a spray of neem oil, baking soda, soap and water in order to keep the septoria and mildew at bay. A day or two after I sprayed them with the neem oil, I started to get some hairy white mold growth on the top of the soil. I carefully scrapped it off and then gave a slight spray of white vinegar and water over the top. After two days, it’s returned and I’ve done the same again but removed the top half inch of soil and replaced it with fresh soil this time.

    Whilst the mold/mildew is a problem in itself, I hope that I’ve got that one covered with the neem oil and moving them outside. The real problem is the potential deficiency I have on my hands: like I said, the newer growth started turning light/lime green again about 2-3 ago, and over the past week it’s become increasingly worse with the leaves starting to curl and develop yellow/brown patches.

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    It will only let me insert 5 pics so I'll post some more below.

    Anyway, I’ve tried to identify the problem myself and it seems like it could be anything! It seems to be most likely a potassium and/or phosphorous deficiency. However, a lot of the info I’m finding online is contradictory: some places suggest I have not enough potassium and/or phosphorous; whereas other places suggest I may have too much! In any case, I could really do with some more experienced eyes taking a look at the pics I have and giving me a steer on what the problem is and what I should be doing to remedy it.

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    Default More Pictures

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    Are you watering to run off at least 10 to 15%? If not that can show all kinds of deficiencies.


    You are a little bit nitrogen toxic on those lower leaves which isn't really going to be an issue seeing as how you're growing photos. You have mostly sulfur deficiency and some calcium and magnesium showing just a little bit. I'm not sure if you get sulfur magnesium or calcium in the nutrients you've been using or not? You should check the bottle but I kind of believe you're not.



    J

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    Quote Originally Posted by jingo View Post
    Are you watering to run off at least 10 to 15%? If not that can show all kinds of deficiencies.


    You are a little bit nitrogen toxic on those lower leaves which isn't really going to be an issue seeing as how you're growing photos. You have mostly sulfur deficiency and some calcium and magnesium showing just a little bit. I'm not sure if you get sulfur magnesium or calcium in the nutrients you've been using or not? You should check the bottle but I kind of believe you're not.

    Hi jingo,

    I'd say something like 10%-20% run off, yea. Maybe I haven't been too strict with it. I'll keep an eye on it. Thanks!

    Ok. The nitrogen toxicity is interesting. Super Silver Haze is pretty demanding when it comes to nitrogen so I went with the guano to try on ensure it got enough nitrogen. I guess the guano may have been a bit too heavy on the nitrogen and not heavy enough on sulphur, calcium and magnesium, etc. I've checked the nutrient info on the guano label and all it says is this:

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    Given that it only lists N, P and K, your suggestion that it could be deficient in sulphur, calcium and magnesium seems likely. Luckily, I ordered some new nutrients a couple of days ago when this started getting worse a couple of days ago. The new formula is this:

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    and "also contains: magnesium, sulphur and boron."

    I gave them a foliar spray with the new nutrients and a light feed to settle in the new top layer of soil this morning. Hopefully that should help.

    Apart from focusing on getting enough run off and using the new nutrients, is there anything else you'd recommend? Should I get rid of the affected leaves or leave them alone?

    Thanks again!

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    That formulax looks pretty good I didn't see the sulfur and magnesium on there, but you probably saw it somewhere else. You can always use unscented pure magnesium sulfate which is epsom salts. And do foliar feeding anytime during the grow up until about a third of the way through flower.

    I like to leave the affected leaves on there and watch and see if I can stop the progression, if not they're at least volunteering their nutrients to the rest of the plant. Once they start blocking bud sites or get so crispy that they can't give up any their nutrients, then I remove them.



    J


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    By the way, welcome to the forum and a big thumbs up for reading through and finding that form to submit your issues.



    J


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    Quote Originally Posted by jingo View Post
    By the way, welcome to the forum and a big thumbs up for reading through and finding that form to submit your issues.



    J
    No problem! Thanks for the help, man!

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    Welcome to the Talk dude, enjoy.

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