Identify problem marijuana leaves

A question from a fellow grower:

Could you advise me as to why this problem is occurring to my leaves

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Look forward to the response as I am having similar issues.

Look up the post titled “my guide to sick plants”,print it off and save it

Looks like it could be a pH issue. Red stem of the leaf, burnt looking or withering tip, and spots or freckles, all pointing to a likely nutrient deficiency or toxicity from a bad pH most likely.

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I am new to growing autos I have a 2fast 2vast she is 6 weeks old and is 26in.tall and bushy as bushy can be but she has yellow on the tips of my fan leaves and am stumped to way it is doing this

Sounds like nutrient burn, maybe pH.

What is the pH and nutrient concentration (EC/TDS/PPM) at your root zone?

just under 7do you think flushing with water would help

So pH is under 7? Or EC is under 7? An EC near 7 is way too high! A pH of just under 7 is usually ok in a well balanced soil medium but too high for hydro.

I’m thinking that is probably your pH. But I still think your EC/PPMs are probably too high, nonetheless.

A flush with properly pH’ed water probably would help.

I don’t know what ec/ppms are? what do you suggest I do

EC is the Electrical Conductivity of the nutrient salts in your growing medium, soil or nutrient mix. Some meters are called TDS meters, this stands for Total Dissolved Solids, another way of saying dissolved nutrient salts, and usually these meters do the conversion automatically for you to a PPM, or parts per million readout. This PPM meter might be a bit different, depending on who’s scale you are using, there are 3 major ones, The USA, Europe and Australian, most name brand meters will be using one of those area’s conversion, but the pure EC number is always the same no matter where in the world you are.

Some soil meter probes, you can sometimes find these at local nursery/garden supply places easily, and sometimes they can read pH, moisture, and “nutrient fertility” again, just another way of saying “nutrient concentration”.

You can find various digital pH meter pens and TDS pens at amazon and e-bay, they have $10-$20ish pH and TDS meters that will work very well, the rating and reviews will likely point you to affordable products with a good measuring accuracy. If you get a TDS/PPM meter make sure it reads well above 999PPM and has temperature compensation.

And check out this blog by Robert to help understand some of the ways to use these to get a general idea of what is going on in your soil.


I will run a n-p-k test to night and see were I stand with that I did a PH test and it is a solid 7.I will post

BTW, your pH would be better at 6.5, in soil. And pictures could help as well with identifying the problems appearing in your leaves. But I’m betting your NPK test will show your nitrogen, at least, as way too high, unless you’ve already flushed. And if you have flushed, it will still be good to know where your soil is at as far as your NPK values are concerned.

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how do I lower the PH

Check out this thread: Lowering the pH of my water

Hi I too have a problem with just one of my plants the two lower main fan leaves have turned to this…Could someone please help me? Thx. .

Same advice as above, it’s probably pH. We need to know the pH of your water, and of the root zone.

yes it has crossed my mind but I have 8 going all have received the same water and nuts but its just my one WW thats showing this. its a soil set up, getting litmus paper tommorow will let u know whats ph at roots and upper soil level. thx

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Also, check out Latewood’s support ticket check list, maybe you’ll notice something especially relevant to your situation that you haven’t thought to mention.

Also just having these detailed parameters of your grow could help us identify anything else that might be contributing.

Macstoner thx for advice, whats the link for that support ticket thing mate? I checked my PH 6.5 going in, run off 6.3, and getting between 6.1-6.3 form the root area. I think it could have been a bit of mag loss, been putting cal mag in all of them but I think by accident I did not give my WW much, need to get more organised, got meself a white board and pen now, going up market now. Finding it hard now the summer is kicking in over here UK keeping my temp at 75 deg, keeps going upto 80, sometimes 85, I have two fans one osc at bottom pushing C02 up one at top running over my 600w hps, a 5" extractor fan to carbon fillter and a 4" fan pushing fresh air in but have to keep opening door all the time, might have to switch to a night time 12 light and dark day time i think, but cant really do it now as im in flowering mode all ready made one time error by my timer going tits up and gave them 16hrs of light in early bud but i gave them some rest and switched timer and seem to be coming on fine. any advice about how to change to a night time 12 light would be helpful tho guys. thx

The support ticket is like a checklist of all the parameters that might be in your grow. For example answering all of them might help us see something we were not aware of in your grow that might be a contributor to your problems.

Like knowing what nutrient system you are using and at what PPM’s could help confirm or rule out a cal/mag problem, but it seems you might not be following anybody’s nutrient system, or if you are, like you said, maybe you forgot to give that one as much, which confuses me because usually most people or nutrient systems I’ve seen all have you mix all nutes together in a large container, have them stabilize and tested for pH, and then that is poured onto the plants so everyone is getting the exact same stuff.

Anyway, it seems you identified the likely cause of the problem, sometimes filling out the list helps us get there quicker and sometimes it doesn’t, so it depends on whether I point the link to it, sometimes I do and sometimes I don’t.

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