What are these brown splotches?

I noticed this on a few (VERY few) random fan leaves; and they are middle leaves. Plants still look OK but don’t want to waste this opportunity to learn or maybe catch something early. I’m in soil and recently flushed with Sledgehammer and have been trying to get my soil pH a bit higher. Last runoff ranged from 6.25-6.55 which is as high as it has been in a while. After researching a bit my guess is pH stress. Sorry for crappy pics, the color resolution on this phone camera inside its case is poor. These are not ‘spots’ or ‘dots’, they are splotchy. Leaves are all still pretty much green.

Here’s a canopy pic, they actually look pretty perky to me.



Don’t flush with anything and plan P H water that’s it. But yes you are catching it early.
It still could be a couple of thing and one could be this. your’s is earley stage so it’s more
.difficult to figure out just what it is.
This pic is very similar to yours but in a later stage of > Manganese


And then there’s this one> Potassium


This one here is BROWN SPOTS


Now please read this cause I believe I got this thing figured out.

A magnesium deficiency, as manganese deficincies are mostly characterized
by interveinal chlorosis which is a yellowing of the leaves between the
veins with the veins remaining green. The browning spots is called marginal
necrosis which is usually caused by a calcuim or magnesium deficiency.

A magnesium deficiency can be quickly resolved by watering with 1 tablespoon
Epsom salts/gallon of water. Until you can correct nutrient lockout, try foliar
feeding. That way the plants get all the nitrogen and Mg they need. The plants
can be foliar fed using ½ teaspoon/quart of Epsom salts (first powdered and
dissolved in some hot water). When mixing up soil, use 2 teaspoon dolomite lime
per gallon of soil.
If the starting water is above 200 ppm, that is pretty hard water, that will
lock out mg with all of the calcium in the water. Either add a 1/4 teaspoon per
gallon of epsom salts or lime (both will effectively reduce the lockout or invest
into a reverse osmosis water filter.
Mg can get locked-up by too much Ca, Cl or ammonium nitrogen. Don’t overdo Mg or
you’ll lock up other nutrients.

Calcium deficiencies are difficult to distinguish visually as excess calcium may
produce deficiencies in magnesium and potassium.

Now I say do the Epson Salt thing and give it some time and I do believe you’ll be a happy man.


Thanks @garrigan62. I use RO water plus CalMag for all watering…nutes or not. I also put dolomite in the soil in these pots, around 1 tsp/gal of soil. I’ll watch it like a hawk.

Hoping I’m just a little off and can get back on track. That’s kind of been the theme of this first grow so far…slightly off target but not so much that the girls die or get really unhealthy. Probably fairly standard for first grows. :+1:


Take a look at your calmag. It probably has decent amount of nitrogen and calcium. Your dolomite lime will also add calcium. If you start getting a little high on those elements they can lock out others too. I think Garrigan65 has you pretty well set .

@dbrn32 Cool, thanks.

If you look closely at the leaf on the left in the second pic you can see that the veins themselves are a bit brown. Not sure if that helps.

It is def getting worse. This is the same leaf as the second pic above, 24 hours later. And more leaves have it but the 2 Chocolopes on the right still don’t have it…yet.

Since my TDS was high at last watering+nutes at half strength (but still not even close to the lofty numbers on the Fox Farms soil chart) I just gave them plain water and TDS was still high (all were in the 1050 ppm neighborhood). But pH was low again. The 2 problem plants were 5.5 and the 2 plants without this browning were at 5.8.

This is so frustrating. Fox Farms Soil chart says feed every other watering (BS), it says use Big Bloom at EVERY watering (BS), it gives enormous numbers for TDS (more BS). I don’t even come close to giving these plants those amounts and my TDS seems to magically rise (I’ve never given my plants 1050 ppm but my runoff is 1050 ppm, and has been even higher) and I give them water or nutes at 6.6-6.8 pH but my runoff always drops over time. I always have significant runoff. And I’m using their soil too. Whiskey Tango Foxtrot! :face_vomiting:


Fox Farm tends to acidify the soil. Your plants are probably in the process of locking out nutes. In soil, plants won’t really have access to Calcium once the pH of the medium goes below 6.

Also, your soil has its own ppms. So, when you water/feed your plants, some of those soil nutes get released, making your ppm reading high.

How old is your plant? Fox Farms does recommend occasionally flushing when using their line of nutes.

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What size container are you using for your soil grow? Size of container will directly effect your ability to control such things as nute issues and the smaller the container the more difficult issues like this will be to control. I’m willing to say if that plant were in a 20 gallon container you would have no nute issues. Now watch as you say it is in a 20 gal lol oh yeah I agree with what everyone else has said. Container size …

I had watered twice and then used Sledgehammer for the first time (so that’s 3x waterings with no Tiger Bloom or Grow Big) but I did ‘chase’ with Big Bloom a couple of those waterings. So the first 75% was just RO water plus CalMag and the last 25% had Big Bloom. Which Fox Farms says you can use Big Bloom at every watering. And I’m not even using full strength. Why would their dosages be so high? They’re not increasing sales by getting me to use a couple extra teaspoons only to have my plants suffer.

Oh yeah, I switched to 12/12 just after Christmas so this is week 3 of flower after a 9 week veg. The space in the third pic of the original post is 4x4 if that helps to provide some context for size.

They are 5 gallon pots.

Thank you both for your help. Time for a beer…since I got nothin else for at least 7-8 weeks. :sob:

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Take heart there. Been there done that and still I screw up royally usually during flower lol. 5 gallon pots !!! That’s way too small for any strain of feminized cannibis and I’m willing to bet the “ pot” lol that’s your problem that’s causing the nute issue. Try as garrigan said foliage spray but do it lights off and I wash the leaves off after an hour of foliage spray. The plant sucks it up in less than an hour just make sure you wash residual spray off before lights on or burn is likely to occur

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But your pH & ppm’s are still off. What were your run-off readings after the flush? When you flush, you’re trying to get your ppms & pH in good range.

PH is so important. You must get it into range.

Do you mean foliar ALL of the fan leaves or just the discolored ones? That is ton of spraying/wiping off if it is all the leaves. These girls have not even filled out these 5 gal pots…I don’t think.

After Sledgehammer flush the TDS ranged from 400-800 ppm. So I thought it was OK to give them 1/2 strength Tiger Bloom prior to this watering. The ppm of that nute solution was around 750-800 ppm which I thought was about right…even though it’s half or slightly less than those bogus numbers on their soil chart.

Personally I’d flush with distilled water available at any groc store. Then I’d gently remove the entire root ball and if it meant destroying the container it’s in to do it then that’s what I’d do and get it in a larger container with good organic blend soil. Water it and it will recover if you don’t damage to many roots. As it is now idc what you do since your in soil and in such a small container your nute issue will continue and most likely your grow will suffer greatly or die. I don’t mean to be so disheartening about it but it’s true and I’m not going to sugar coat it. Your entire problem is the container and that’s what caused your issues so deal with the problem not the issue.
As far as foliage spray , if you intend to keep them as is then using a foliage spray is your best option. Mix as garrigan said and spray the entire plant , wait about 45 minutes to an hour and then using distilled water wash the plant in the same manner you used foliage spray. Experience has told me to wash the leaves after spraying them or light burn is nearly guaranteed to occur. My opinion is to transplant now and forget trying to save them in those small pots please

I grow in five gallon containers as do many others and I don’t have issues. Could you elaborate on your theory??


Look, I have told you what to do and I don’t believe you have even started to do it. So with that being said there is nothing more I can do here.
You keep on that road your on with the ca-mag and what not you will lose them.
I’ll be stopping by from time to time



Sure the size of your grow container when growing in a strictly soil medium directly affects your ability to use nutes effectively , the size of the plant is effected, the container size is in direct relation to the size and growth of the plant. Ever heard of a rootbound plant ? The roots can’t expand neither can the plant. I’m not a scientist but not only common sense tells me this but more experienced growers know this to be true. I don’t provide web links to stuff because with several finger strokes you can discover all this for yourself and more about root vs plant size etc. As far as strain genome etc auto fem etc there are exceptions when a plant is only meant to get so big and in that case it takes much much longer for root issues to present themselves but they will show up just a matter of time. Ever seen gma transplant her flowers ? From smaller containers to larger ones ? What y suppose she did that for ? I relent that a 24 inch seed to harvest speed bud strain can be effectively grown in a 5 gallon pot but not a 6-8 wk vegging fem going into 8-12 wks of flower nope nope and nope lol

Maybe I misunderstood, the first line of your post said flush with plain pH water which is what I did. I have my Epsom salts ready but was waiting for guidance because you mentioned dolomite which I already had in the soil. Did I misunderstand? Thanks for your patience.

Yes I wanted you to start doing the Epson salt a.s.a.p. . Trust me use " NOTHING ELSE ! "
Put Epson salt for each watering. And you will see a bid difference in no time. I know this for I fact cause I use Epson sale on mine when I had the same thing on my last grow. And all is good maybe misunderstanding on both sides…lol

Got it, I prob still need to flush further since pH is low so I will add Epsom to this last flush and going forward. They are drinking like crazy so I’ll have to water again very soon. Thanks so much brother. :+1:

Fabric pots air prune, which means when they grow out of the fabric, air actually kills the over grown roots, making it impossible for the plant to become root bound. I’m pretty sure I never saw my grandma using fabric pots :wink: