Yellowish Spots on Leaf Margins and Burnt Tips

Hi All,

I noticed these yellowish spots on the leaf margins and tips look burned. It looks to be isolated to the leaves midways up on the plant. The very top leaves look great.

This plant is about 2 weeks in from the start of flowering (pistils). Overall it has a nice green appearance.

What do you’all think is the problem?

Here is info on my grow:

• What strain: AK-47 from ILGM

• Method: Organic soil, FF Ocean Forest amended with Dolomite lime, Garden Tone, Worm Castings, Perlite and Mykos applied to roots during transplant.

• Vessels: 3 Gallon Fabric Pots

• PH of Water, Around 7ish

• PPM/TDS or EC of nutrient solution NA

Indoor or Outdoor

• Light system: (3) Growstar LED, 115 watt actual current draw each, 14" Above canopy 22-29K LUX— estimated PAR 800-1050 ppfd/umol/s/m2., DLI about 30 mol/m2/day

• Temps; Day- 75 deg. F , Night- 75 deg. F.

• Humidity; Day- 55% RH , Night- 55% RH

• Ventilation system; Separate intake and exhaust fans providing 5 air changes per minute roughly

• AC- 8k btu portable , Humidifier= yes, De-humidifier= YES,

• Co2; Yes, No

If growing Hydro some additional questions: NA

Here are the results from my slurry test yesterday:


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Dark, waxy leaves + burned tips = nitrogen toxicity.

I would ditch the Garden Tone and use a proper cannabis fertilizer like GH, AN, Fox Farm, or Jacks.


Agree on the appearance of nitrogen toxicity. I would also ask where the slurry sample was taken from, as in how close to the root zone? The burnt tips and edges are most likely from the FFOF and amending it with the Worm castings that have additional nitrogen. Take a run off sample on your next feeding and check that PH and PPMs :love_you_gesture:


Thanks MidwestGuy… That makes perfect sense. The yellowing of the leaf margins didn’t fit with all these charts I have.


Thanks for the reply. I scrapped all the top dressing out which was a maybe an inch in thickness… then dug down about 2" to get the soil sample… I was definitely into ‘some’ roots.


Good deal, seems you have this under control for a plan of action :love_you_gesture:


Still on this steep learning curve. So, I have learned I can’t trust my slurry test results. I started a slow flush and sure enough runoff EC was really, really high.

I was under the impression slurry tests were more accurate than runoff. Especially since I am all organic I only water enough to just barely get any runoff if any.

What are your thoughts on this?

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Organic as the soil is completely living requiring no added nutrients? If you were adding nutrients and not to run off that could explain your high numbers. Slurry test are accurate but require samples from in the root zone and sometimes risky on younger plants and the potential for root damage.

That initial run off is what’s sitting in the bottom 1/3 of your medium and pot. Catch the last bit coming out and those numbers should be considerably lower than the first of the run off :love_you_gesture:

Thanks, I will see what I can get it down to

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This really just blows me away. I am embarrassed to even show these numbers. I just really trusted my slurry tests, did my best to dig down 2 or 3" to get a decent soil sample.

Here is where they were this morning after my initial flush and testing about 200ml of runoff. AK pegged out my meter!


But, other than a few tips burnt and those yellow spots they don’t look bad:

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It is shocking especially how well they look. The PH is also concerning. Personally I would flush these with PHd water at 6.0-6.5 to bring the PH back in range of 6.5 that will also flush any salts and minerals that have built up in the root zone. It’s going to take flushing at 3 times the pot size. Catch the last drips of the final flush and test those numbers PH and PPMS. My sweet spot is 900-1000 on the PPMS and 6.5 on the PH. Follow this flush with a nutrient mix at those numbers above and a feeding of beneficial microbes :love_you_gesture:

Organic ppms tend to be pretty skewed. Especially if your doing it properly. Ive seen ppm’s above 3k straight out a bag of FF, and above 4k with my emulsion. And seen member with it around 6-7000 with happy plants.

Most amended goodies need to break down to be readily available so even a skyhigh reading isnt all available to your plant.

That being said, it was mentiond at the top. The additional N heavy amendment combined with FF soils maybe why your seeing numbers this high. Id definitely look into a more canna friendly nutrient line

Great info, thanks!

Can I get your thoughts on my methods and nutrients?

This was my initial soil mix:

I did a top dress the day I flipped to a 12/12 lighting schedule. Last grow it seemed like I ran out of nutrients a week or two after the first sign of pistils. I was trying to anticipate it this time.

I appreciate you help!

The NPK values of each will be helpful. Ill try but at work, so if I disappear, dont fret.

FFOF - Complete Soil… no telling the NPK but we can guess its solid.

Espoma Garden Lime - Dolomite stuff. Its excellent for maintaining healthy soil pH when amending. Most amendments drop pH like a rock. This helps keep it around 6.5. No NPK as its diff types of Calcium and Magnesium (no calcium nitrate AWESOME)

Espoma Plant Tone - 5-3-3 NPK General all encompassing feed. The problem with it is you cant lower the nitrogen and push phosphorus and potassium as you get later into flower. Not a sound amendment for grow herd. ALSO TIME RELEASING, FLUSHING MAY ONLY BE RELEASING MORE INTO THE SOIL this maybe why you saw runoff skyrocket as well. If so expect some burnt tips and unhappy girls sooner then later.

EarthWorm Casting (EWC) - you can almost never have too much of this stuff. Use as liberally as you want (just not more then the soil :crazy_face:)

Kelp Meal - GOOD STUFF. Idk what brand you may have but most generally is… 1-.5-2 NPK. Not really super important because it isnt very heavy NPK wise but good stuff all the same. Which brand?

Perlite - I always use this around 1:3 ratios with the soil. More will just make it fluffier and drain faster, less more compact and drain slower. Make sure to avoid nutrient soakd perlite (MG makes one I bought when I started. Tricky buggers).

Espom Salt - excellent source of magnesium and sulphur.

Food Grade DE - excellent pest deterrent.

Gypsum - this Im less familiar with but heard good things. Good source of silica, calcium, and sulphur? I think its used primarily in veg however.

As to the amounts… id be less help there. My super soil came out HORRIBLY. But a few of those amendments I mix into my teas when I feed my soil. So decent list.

Remove the Plant Tone. Add something more canna friendly. And ur fine

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I really appreciate your help and don’t worry about me, take care of work and I will be here. Whatever is done is done. Honestly, I am not too worried… yet.

You probably didn’t catch my switch on the tone. I started off with plant tone in my mix and switched to garden tone with the top dressing. Because like you said the plant tone has lots of N.

This is the garden tone:

still pretty hefty with nitrogen.

I use Dr. Earth Kelp Meal, here is the label for it:

And yes, I use the Gypsum for calcium and sulfur:

What can you suggest for Potassium and Phosphorus in the way of a dry amendment? I have been using unsulfured Blackstrap molasses once a week with my watering to feed the little critters but got a concerned about it for some reason. Maybe too much K?? and it does have N too.

Like, I said; no rush getting back to me and I appreciate your advice.

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I completely missed that. Thanks for the correction. And yea, it is relatively N loaded.

MOAB (Mother Of All Buds) was popular when I first started. 0-52-34 NPK… not sure why its not as popular now. Seems decent.

I used Alaska Fish Emul and BuildASoil Thrive.N Bloom, both of which are around 0-15-15.

Dr Earth has ‘Flower Girl’ which I used in a super soil (earlier when I didnt get pH etc etc so it was basically wasted). But its good stuff too.

There are quite a few options. If you want to stay dry? Im looking into Earth Dust Organic dry nutes rn.

Also Ive heard a few growers talking about growdots… both of those are relatively new however, and Ive yet to see a grow with them, let alone use em myself

Sweet! Thanks for the suggestions, I will pick one out and give it a try. I am wanting to stay dry at this point just to minimize my variables, seems like I have enough already.

You have been very helpful and I will reach out if things go sideways again.


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Good stuff Brother PurpNGold!! Appreciate the class :love_you_gesture:

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Anytime my friends. Happy Growing

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