Plant Deficiency diagnosis

WintersBones

Well-Known Member
Can anyone help me confirm what deficiencies or problems I'm dealing with here? I suspect Mag and Phosphorus deficiencies, but also seeing signs of Nitrogen toxicity? I'm growing in coco under LED's and CFL. Four Auto's, 19 days since sprouting but they are small and growing slowly, only 2.5-3" tall and just working on their 4th nodes. Roughly following the 'Coco for Cannabis' nutrient watering schedule for GH Flora series 3 part, with CalMag, Nectar and recently started adding some EpsonSalts, with input PPMs between 350 to 650 and pH'd to around 5.5-6. I've been dealing with pretty hot runoff for awhile which must be causing these issues with the plants, so every other watering or so I've just given a low PPM pH'd CalMag water with no or very light nutrients trying to get the output PPM's down. Also started giving a CalMag foliar spray the last couple of days.

Symptoms: I'm seeing dark and shiny areas on older leaves and down-turned tips. Some yellowing/lighter green along the veins and reddish stems ( that might have been also from light burn). One plant has just been generally droopy and sad looking and every plant has showed at least one odd leaf growing strangely or missing a part at some point.

Runoff has been as high as 900-1100ppm/1700-2300uscm & pH between 6.9-7.6
Most recent test showed btween 650-715ppm/1440-1521uscm & pH 7.5-7.6

So I'm getting the PPMs under control gradually, but the pH output is still very high. Am I doing the right things here? Should I lower the input pH even more to try to get the runoff pH down further? And isn't it strange to be having a Nitrogen toxicity in early Veg stage like this? Or is that due to these other issues? Any advice is really appreciated! I feel like I'm a week behind in growth now from where they should be and worried the plants wont be very big when they hit flower in another week or two! TIA

Droopy leaves & Discoloration
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Odd Growth
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the two looking not very happy, while all plants show minor symptoms these are the worst.
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Renfro

Well-Known Member
Grab a bluelab soil ph meter, it's the best move you can make. Then you can really see what the soil pH is and feed correctively.
 

Renfro

Well-Known Member
Did you wash and buffer the coco before using it? The high runoff PPM makes me think it's still "dirty".
 

WintersBones

Well-Known Member
Did you wash and buffer the coco before using it? The high runoff PPM makes me think it's still "dirty".
Ya this is my first run with coco and it is very possible i didn't do a very good job with my coco prep. Any suggestions on how to compensate at this point? More flushing with CalMag? Its mostly the the pH that i can't seem to put a dent in.
 

Renfro

Well-Known Member
It was covered in this thread yesterday, it seems to be a very common issue lately.

 

WintersBones

Well-Known Member
It was covered in this thread yesterday, it seems to be a very common issue lately.

You're referring to the over correction method right? That is generally what I've been doing, just not as extreme. I'll step it up and try to get it under control.
 

Tib420

Well-Known Member
Its coco not soil. I really doubt I'm over watering, and shouldn't let coco dry out, would only spike my PPMs.
if you let it dry out and give it plain water at 5.5ph and like a 150ppm. it'll flush out your high dose of nutrient you gave this plant. 900-1100ppm? that's like week 7-8 of flower. You plant is on it's 2nd set of leaves. 650ppm is for like week 3 of veg. let your plant get an established root system before you start blasting it. Your run off should be 5.5-5.8 i know rockwool has lime in it and has to be pre-soaked for 24 hrs or it will run your ph up to 8
 

WintersBones

Well-Known Member
if you let it dry out and give it plain water at 5.5ph and like a 150ppm. it'll flush out your high dose of nutrient you gave this plant. 900-1100ppm? that's like week 7-8 of flower. You plant is on it's 2nd set of leaves. 650ppm is for like week 3 of veg. let your plant get an established root system before you start blasting it. Your run off should be 5.5-5.8 i know rockwool has lime in it and has to be pre-soaked for 24 hrs or it will run your ph up to 8
Ive been alternating with a seedling strength watering around 400ppms with just CalMag water at around 250ppm at 5.5 until recently. I'm getting the PPMs under control, but its the pH that's being so stubborn. As Renfro mentioned, a poor buffer of the coco is probably why i had high PPMs initially and now the pH issues and the Mag deficiency. I'm a little confused why it also looks like Nitrogen toxicity though. I've backed off the N now and being more aggressive with a lower input pH. We'll see if that helps. The plants are still growing, but ya its slow going...
 

WintersBones

Well-Known Member
Plant looks pretty good to me. why suspect deficiency when your ppms are so high?
It was the initial output PPMs and high pH when i was feeding at a much lower level that had me confused. I'm now mostly trying to figure out the right adjustments i need to make to my nutrient mix to compensate for my error with the coco buffer.
 

WintersBones

Well-Known Member
what is meant by coco buffer? was there something in the coco when you started?
When using coco you are supposed to wash it first and soak it in CalMag water to clean and buffer the coco. The coco otherwise likes to hold onto CalMag and not release it to the plant. I dont think i let it soak up enough CalMag, so my coco isnt buffered properly, so it's now taking away some of the CalMag I'm trying to give to my plants, which is throwing off how the plants are taking up nutrients. Might also be contributing to my pH issues, though I'm not 100% sure about that.
 
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