Discolored leaves... N or mag deficiency?

Good day

First time growing, it's been lots of fun though the amount of time in researching and taking care of them feels like a second job. It's quite the all consuming hobby.

Anyways, my plant is growing nicely and getting quite large (about a foot tall, 2ft x 2ft) but there is quite a lot of discoloration in the leaves that is giving me some concern.

I'm growing in coco, the plant is about 6 weeks old in veg and it's probably an F2 sativa hybrid of some sort.

She is growing under 90 watts of quantum boards (and in the vicinity of another 60 watt QB) about 2 and a half feet above the canopy. I'm not sure if the discoloration can be attributed to the color temperature of the LED's playing tricks on my eyes, or if it is just a strain that just ends up looking like this in veg. I had the lights a bit lower (2 feet above) and had it up to 105 watts but felt like the problem could be linked to too much/too close light so backed it off.

Currently, I've been feeding about 2 grams Peters 5-11-26, 1.9 grams Calnit and 950mg of Epsom salts for a PPM of about 800 (filtered water is 100ppm). Sometimes I'll mix in kelp and fulvic.

I usually feed at 5.8-5.9 PH. I learned that magnesium absorbs better at 6-6.2 but in an effort to help increase nitrogen uptake and fix the leaf problem, I've not really staggered the PH above 5.9.

Though the leaves at the bottom are quite yellow relative to the upper leaves, now I feel like my problem might not even be a nitrogen deficiency but could be magnesium instead.

Should I increase the already seemingly high PPM's on my next feed? Would it be better to boost the PH to 6.1 or 6.2 for a few days? Is it possible that I have some nutrient lockout and should flush?

Please take a look at the picture and if you have any advice I'd appreciate it.

here she is

A couple things to note, one, the feed you're giving, is abnormally high in potassium, even phosphorus, especially in veg stage!!! You can use that during the transition phase as that's when the nitrogen to potassium ratio is very important to help induce flowering, but for now, that excess potassium may be locking out your magnesium, which is what the plant is showing a deficiency of, the most. I say possible lockout due to excess potassium, because even on the new growth, you can see how extra skinny it is, that is one symptom of excess potassium (phosphorus will do the same in excess).
Just of note, from the pics, this seems to be an indica dominant plant rather than sativa. Also, don't lower your ph just to have nitrogen absorbed...nitrogen is the most readily available element throughout the ph range..if you are not getting nitrogen uptake due to ph being too low or high, then you better believe that everything else would be locked out as well! Also, humic acid is better for your medium with the kelp than fulvic acid. Fulvic acid with kelp, is better for foliar feeding as fulvic acid has a lower molecular weight and can be easily absorbed by the leaves, humic acid is heavier and better for the medium.

Thanks for the input Blitz, it's always great to have someone share the experience they've accumulated.

Blitz35 said:

A couple things to note, one, the feed you're giving, is abnormally high in potassium, even phosphorus, especially in veg stage!!!

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Are you taking into account the addition of the Calcium Nitrate?

The nutrient PPM of the feed is around 100-24-108-93-25 (N-P-K-Ca-Mg). I've been reading up on various nutrient regimens and these ratios seem to fall in line with the norm with the exception of the high CA. The other alternative I've seen is to follow the Jack's 321 formula (142-49-205-114-93), which is even higher in potassium and has a different CA:MG ratio than I've seen recommended. Looking at these 2 different feeds, I should probably boost the MG.

Blitz35 said:

you can see how extra skinny it is, that is one symptom of excess potassium (phosphorus will do the same in excess).
Just of note, from the pics, this seems to be an indica dominant plant rather than sativa.

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The skinniness is why I thought it was a sativa hybrid more than an indica. It certainly isn't the ET finger style sativa leaves but they are also not quite as bulbous as an indica's. Also the light colored leafs made me think it wasn't an indica but perhaps that's a mix of me wanting it to be a sativa and also the nutrient deficiencies. What did you notice that made you think it was an indica?

Blitz35 said:

Fulvic acid with kelp, is better for foliar feeding as fulvic acid has a lower molecular weight and can be easily absorbed by the leaves

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Do you have any links for why humic is better than fulvic in coco? I thought that fulvic was of a higher quality (and thus more expensive) because of it's lower molecular weight increasing bioavailability.

I just read up on making a foliar feed of fulvic and magnesium sulfate to be applied under the leaves. I will try that out if increasing the amount of Magnesium Sulfate doesn't work.

Thanks again!

How much Magnesium do they get??

Heres a feed chart you can check out. Its for a 4 weeks veg, and 8 weeks flower.


https://hydro-gardens.com/wp-content/uploads/2017/12/Burchetts-recipe-2017.pdf

jimihendrix1 said:

How much Magnesium do they get??

Heres a feed chart you can check out. Its for a 4 weeks veg, and 8 weeks flower.

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awesome! thanks, i'll save it to my grow documents.

based on this, it looks like i can be more aggressive with the PPM of my week 6 veg feed. also, giving 950mg is 20% less than the recommended feed from both this chart and the Jacks 321 formula, so I'll definitely fix that for the next feed.

do portions with nutrient deficiencies generally improve once corrected or are those leaves always going to be diminished?

If you get them before theyre to far gone they will green right up. Some may not make it. Just don't over do it trying to push them. Theyre going to do what theyre going to do, if you have everything right.

gfpeezy said:

Thanks for the input Blitz, it's always great to have someone share the experience they've accumulated.



Are you taking into account the addition of the Calcium Nitrate?

The nutrient PPM of the feed is around 100-24-108-93-25 (N-P-K-Ca-Mg). I've been reading up on various nutrient regimens and these ratios seem to fall in line with the norm with the exception of the high CA. The other alternative I've seen is to follow the Jack's 321 formula (142-49-205-114-93), which is even higher in potassium and has a different CA:MG ratio than I've seen recommended. Looking at these 2 different feeds, I should probably boost the MG.



The skinniness is why I thought it was a sativa hybrid more than an indica. It certainly isn't the ET finger style sativa leaves but they are also not quite as bulbous as an indica's. Also the light colored leafs made me think it wasn't an indica but perhaps that's a mix of me wanting it to be a sativa and also the nutrient deficiencies. What did you notice that made you think it was an indica?




Do you have any links for why humic is better than fulvic in coco? I thought that fulvic was of a higher quality (and thus more expensive) because of it's lower molecular weight increasing bioavailability.

I just read up on making a foliar feed of fulvic and magnesium sulfate to be applied under the leaves. I will try that out if increasing the amount of Magnesium Sulfate doesn't work.

Thanks again!

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Good job on your reading! You're on the right track with your research Epsom salt will help, but foliar feed may be better.
I didn't think with those npk values that the ppm's would equal to what you say, a bit odd. I personally don't run on any specific feed regimen prescribed, i feed the plants what they show they lack when it's time. Something i don't understand about your ppms, you say you've recently been feeding at 800ppm, but in the reply above your numbers of n-p-k-ca-mg, add up to 350ppm, those are the main nutes, what makes up the other 450ppm?

Just my view on the indica, the leaves seem to have some bulge to them, she's likely a hybrid, but i think a bit more on the indica side. The new growth, that skinniness is what suggests that too much p or k (likely k if those ppm numbers are correct) is being applied, and that may be locking magnesium out, especially with the higher calcium ratios as well. What is certain, is those leaves are magnesium deficient!

Im not sure how it relates to coco, but this is one article i found, not the actual one i remember reading once...https://www.maximumyield.com/humic-or-fulvic-acid-what-kind-are-your-plants-on/2/1352

Blitz35 said:

I personally don't run on any specific feed regimen prescribed, i feed the plants what they show they lack when it's time. Something i don't understand about your ppms, you say you've recently been feeding at 800ppm, but in the reply above your numbers of n-p-k-ca-mg, add up to 350ppm, those are the main nutes, what makes up the other 450ppm?

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I also thought it was strange that my PPMs were so out of wack. I'm guessing it's because my TDS meter costs less than a value meal at McDonald's. I may have read something somewhere that TDS meters don't measure the PPMs accurately since each salt affects the conductivity differently. It stands to reason then that I've been significantly underfeeding my plant across the board.

Your way of feeding as the plants require makes sense. I'll have to be more vigilant to measure out my nutrient weights and water volume rather than relying on diluting down with PPM readings.

Thanks again for your help. The plant hasn't recovered yet but I feel like some important knowledge was gained before flipping to flower.

That doesn't look like mg def, which shows up as yellow spotting. Coco grows seems difficult to do. I would just leave out the coco and stick with DWC. That coco will trap nutrients. It will be interesting to see how this works out. If 350 ppm is pretty accurate rising it might be a good thing to do. That pale green color looks more N, but then it's hard to tell. There may be a nutrient or two that is missing from that fert mix.

So from someone who uses Jack's 3 2 1, let me toss my two pennies into the mix. You're at a 2: 1.9 : .95 which is basically a 2 2 1 mix. From my experience, it's best to stick to the 3 2 1 ratio, hence the name of the nutrient scheme. I'm not saying that to be a D', I'm saying it because I've been there. I would seek out a 3 2 1 ratio that worked for you in terms of your EC / Total PPM's the plant can take and go from there. Based on your picture; you're suffering from an Mg deficiency, but this is more a result of your ratio, not the fact that there isn't any Mg in your feed. See if approaching more to a 3 2 1 ratio doesn't make a difference, and then, if you still feel there's a need for more Mg, you can add it via your Epsom Salt. I've used this same ratio from seed / clone to harvest with excellent results, once I dialed things back and stuck to the recommended ratios. I wouldn't raise your over all PPM's / EC until you arrived at a 3 2 1 ratio that gives you the same PPM's / EC as you've been using. Once you do this for a couple days, you'll know if you need to up the PPM's or not. In terms of flushing; I wouldn't bother doing it. Nothing about your plant would suggest flushing it is necessary. I would stick to a 5.8 pH and go from there...6.2 is pushing the upper limits of your pH range in coco. Let us know how things work out for you.

Thinking it over, next feed I was thinking of going about 3.2/2/1.2, which ends up with 104N-40P-182K-92Mg-124Ca-112S for a 660PPM total. The N is a bit low but having such high Ca is making me nervous.

Then I will alternate with higher N vs lower Ca for a few days until I get some Magnesium Nitrate unless I learn otherwise...

I don't understand how you come to those numbers ppm wise. How are you getting ppm numbers for each nutrient you are feeding? I use a 10$ ppm meter for 2 years now and it has never failed me, i just don't get how you know how many ppm's of each element you are giving, especially when you say your meter is likely not functioning well.
As for a 3:2:1 npk ratio, especially in your case where you are switching to flower, to me that would be a mistake, you shoud never have more nitrogen going in than potassium, especially when transitioning to the flowering phase! Phosphorus as well should be given in equal amounts to magnesium, and never more than potassium! Why would you feed higher N when you're planning to go into flower? Alot of oddities, but best of luck, hope it all works out for harvest time!

Does 321 mean more nitrogen, less phosphorus, and even less potassium? In other words, does 321 mean the actual NPK ratio? If so, how do you arrive at this "118N-41P-171K" when it's plain that 41 is way less than 118, and 171 is way more than 41? In light of the fact that mg is being given, probably in more ways than one, it's unlikely to be mg def. That problem usually starts to show itself with yellow spotting. I have to agree with Blitz. This is a strange thread so far.
I'm also confused by this: "As you can see the main difference is the huge amount of CA, which is probably not sustainable, so I've ordered some Magnesium Nitrate and will tinker again when it arrives."
What do you mean by not sustainable, and why would the mg nitrate make a difference?

The 3 2 1 reference is in this respect; It's a (3) part feed system. Part A is 5-12-26 (NPK) which contains all of your micros too, Part B is 15-0-0 (NPK)...this is CalNit, and Part C is Epsom Salt (Mg and Sulfur). The idea being you mix these three parts based on a 3:2:1 ratio.

I'm also intrigued as to how you derived at the ppm's for each element. I'm assuming you're using R/O water or you know the ppm's of your base water? Please share your math if you don't mind. I would also keep in mind too much of one element may cause you issues with others. I think if you're looking to make up PPM's I would focus on adding more of your Part A. Your part B and C components are more for supplementing Ca, Mg and Sulfur, in this recipe than they are the meat and potatoes if you will. Considering you're already adding Mg in your Part C, I don't think it would be necessary to add MgNit at all...but I'm just one man, and you're the gardener so do as you see fit. As to how much calcium would I add...I'd stick to the ratio, so 2 parts of whatever your recipe is, which is plenty.

gfpeezy said:

here she isView attachment 4202133

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Looks slightly like N tox.. the leaves on mine are clawing the same cause I changed nutes but like an idiot gave them full strength..lowered it to a third of recommended dose an they're getting better!

CannaCountry said:

The 3 2 1 reference is in this respect; It's a (3) part feed system. Part A is 5-12-26 (NPK) which contains all of your micros too, Part B is 15-0-0 (NPK)...this is CalNit, and Part C is Epsom Salt (Mg and Sulfur). The idea being you mix these three parts based on a 3:2:1 ratio.

I'm also intrigued as to how you derived at the ppm's for each element.

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I took a screenshot from Greengene's youtube video on Jacks 321. From there, I used Hydrobuddy with the elemental percentage of my versions of Calnit and MagSul and tweaked it to try and approach the numbers as close as I could while maintaining the ratios.

With my nutrients, the straight up 321 gives me N101.4, P38, K171, MG78, CA124.7, S98. Using the proper Jacks 321 nutrients it's N118.9, P41.5, K171, MG77.5, CA95.1, S99.4. The discrepancy comes from the fact that my Calnit is 11/23 rather than 15.5/18. I'm also using Peters 5-11-26 rather than the 5-12-26, which means less magnesium and phosphate than Jacks. My magnesium is also higher in MG than the standard by a slight bit and I use phosphoric acid to PH down so that makes up for it.

I need the Magnesium Nitrate to get high enough nitrogen levels in veg without boosting the calcium levels too much. My sulfur will take a hit but it might be more important in flower than veg, so by that time the need for Nitrogen will be lowered and I can readjust my nutrients again along with some MKP.


Interestingly, Jacks 321 is meant to be a 3.6-2.4-1.2 gram ratio, so there is some leeway to boost the PPM's. Even with MagNit, I can't get up to the N142 recommended by the full strength formula without either getting the calcium or magnesium too high, and I want to maintain at least 75% of the recommended sulfur. So it's a balancing act all around, but that's part of the fun isn't it?

Vinny1989 said:

Looks slightly like N tox.. the leaves on mine are clawing the same cause I changed nutes but like an idiot gave them full strength..lowered it to a third of recommended dose an they're getting better!

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I gave a foliar feed of Epsom salt today (first time ever) and they turned a nice shade of green almost instantly. There is still some yellowing but I plan on continuing to give the Epsom salt for a couple more days.

What are those values saying about each element? Why are those numbers so high? Why are you using two different ferts? BTW, I've read that Jack's and Peters are by the same chemist or company. Can you confirm that? Peters used to be sold in Home Depot.