Advice needed - leaf pics included

Not sure if this is a nute issue or something else, but I could sure use some expert advice. This is my third grow.

This is only happening to one strain (two plants) in my room. Here are some details.

  • 4th week of flowering
  • Growing in FFOF soil
  • Humboldt nutrients
  • This only seems to be occurring on old growth
  • One plant is under HPS, the other under LED
  • It has been spotted on maybe 5-10 leaves on each plant

Any help, suggestions and advice is welcome and appreciated. Thank you all!

Strain; Cookies Kush (from clone)
Soil in pots, Hydroponic, or Coco? FFOF in 3 gal pots
PH of runoff or solution in reservoir? N/A
What is strength of nutrient mix? manufacturer recommendations
Indoor or Outdoor; Light system, size? Indoor. Room 6 1/2’ x 7 1/2’. 1000W HPS on one side, 600W LED on other
Temps; Day, Night: Day- 98F (AC unit is on the way…I know it’s too hot), Night - 80F
Humidity; Day, Night: averages about 50
Ventilation system; Yes, No, Size: 6" inline fan pulling through carbon filter
AC, Humidifier, De-humidifier, - Not yet, No
Co2; No

Welcome to ILGM @BlackShirt.

If we could get you to copy and paste this support ticket into your post it will help the memebers get you the best info they can.

COPY/PASTE: This “Support Ticket” into your forum post. Answer these simple questions the best you can. If you do not know, or do not use something; Just say so = NA
Strain; Type, Bag seed, or NA
Soil in pots, Hydroponic, or Coco? System type?
PH of runoff or solution in reservoir?
What is strength of nutrient mix? EC, or TDS
Indoor or Outdoor Light system, size?
Temps; Day, Night
Humidity; Day, Night
Ventilation system; Yes, No, Size
AC, Humidifier, De-humidifier,
Co2; Yes, No

Add anything else you feel would help us give you a most informed answer.

She do that :slight_smile: @Jmesser80.
What is pH of your water when you feed her?
Look at this chart Nutrient_Chart2

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I will say potassium deficiency… But wait for more answers.
Your pH need to be at 6.5 - 6.8

So looks like Phosphorus deficiency? Phosphorus is absorbed on the relative high side of pH, so perhaps your pH is a bit too acidic?

Show us pics of the flowers! (Not necessarily for diagnosis purposes . . . I just LOVE flower pics! :smile: )


You could be right, M4ur. From the charts you posted, it looks like P is brown in the center of the leaf (like his picture) and K is more spotted over the whole leaf . . .

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Yep… Also maybe some pictures of your nutes will help to (the label from the back) @BlackShirt

Thank you for the kind replies @arpeggio @M4ur @Jmesser80

And - @M4ur - that chart is phenomenal - thank you!

So… full disclosure. I’m efficient… nope… I’m LAZY.

Here is what I did. On my last grow, I mixed up my nutes and measured the pHs every week as the concentrations of each nutrient changed. All fell within (what I felt was) the acceptable range without adding pH up or down - so I just kinda called the pH good and haven’t measured it since.

That being said… The pH of the nutrients for flowering week 3 - which I just finished was 7.0 (maybe a touch high). For flowering week 4 (that feeding should be tonight) the pH was 6.6 (better).

Everything I was trying to do the first two grows was so overwhelming that pH-ing the nutes every time was something I was not prepared to handle. Now I can (and I know that I should).

Long story longer… here are some pics of the back panel of the nutes.

And a flower pic - but this is from a week ago. New ones to come soon.


Yeah she added it to the post, when I looked at it originally she didn’t have that portion at the bottom👍

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Could be potassium deficiency. Cannabis plants tend to use more during the fowering period. You might just need to add slightly more nutrients for your next watering. If your PH is around 6.6 as you started that should be ok for a soil grow.

Sorry @Jmesser80 I didn’t know.
@BlackShirt you mix all nutrients in water, right? If your nutes have a schedule feeding I hope you do like they say. I don’t know how to make her better but if I was you I will give her a good dose of potassium (something what have a lot of that) but be careful to not burn her, just full strength (what they say in the back label) and I will pH it at 6.6. Also you need to water her and collect the runoff and test it…

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Flower looks beautiful! Thanks!


@M4ur Yes - all nutes are mixed with water (tap water that sits for 48 hours) and I follow the feeding schedule religiously. I will look into getting her a bit more K

@Jmesser80 - I edited my post and added those items (sorry for the confusion!)

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@M4ur no worries brotha👍

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Not a problem @BlackShirt :+1:

Okay … several lessons learned today.

  1. If you’re new to growing … pH your nutes. I heard it 23497204320 times, but now that I’m dealing with the issues from NOT paying attention to the pH, I can tell you. JUST DO IT.

  2. I noticed purpling of the stalks. If I am not mistaken (it will be the first time today), that is a hallmark of a phosphorous deficiency. Feel free to correct me on this…

  3. The pH of the nutrient mixture I just prepared was a 6.1. This explains the phosphorous (and other key nutrient) lock-out, as P is only absorbed between 6.5 and 7.0.

So … a few more questions…

A. Do you guys pH adjust when feeding straight water?

B. Will adjusting the pH of the nutes to 6.6 - 6.8 or so SOLVE my problem - or is this just what I have to deal with for the rest of this cycle?

C. If adjusting the pH is not a solution, is there anything that I can do to get this grow back on course?

Thank you all so much for your help. This is proving to be a most helpful and generous community.


Before you do any thing flush, flush ,flush…
If you have a lock out nothing else is gonna help quickly.
When watering plane water always ajust ph.
Ph water will help but Will take a month to get straight, nute lock out is cause by salt build up and a chemical flush is needed. Check with your nutes company they should have a flush just for your nutes. Aka same brand.

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I will say “heat” is the cause. Cell damage occurs when temps get above 90f. Or below 50f. Not to mention that when temps are that high the plant photosynthesis does not process at 100%

Get the temps in line between 70-80f before trying to fix the issue.

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I don’t notice the temperature @latewood… Next time I will.

I was replying to this from original poster: Temps; Day, Night: Day- 98F (AC unit is on the way…I know it’s too hot), Night - 80F