Yellowing leaves with brown spots progressing

Hello I have a plant that recently started turning yellow with brown spots. Not all leaves are affected but it seems to keep progressing. I noticed it after giving the plants some cal/mag and thought maybe that was the problem but I’m not sure. I feed with the fox farm trio and beastie blooms every other watering which is every 4 days. The other watering I water with molasses. I am not using grow big. 1 other plant is starting to get some lighter green leaves also. Can it be too much nutes.? Only feeding at half strength. Thanks . Will post a better pic later tonight when I get home but here are a couple.

Problem:yellowing leaves/ lots of brown spots

Medium/grow method:fox farm ocean forest and happy frog 50/50

Feed: and supplements used:fox farm big bloom and tiger bloom at 1/2 strength. Also beastie blooms. I feed 1/2 strength every other watering. And water with molasses between feedings. Feed water feed water…

water source: I use tap water. It comes out about 7.5ph and about 80-90 ppms. I ph up and/or down to 6.3-6.5ish

PH in the root zone: usually similar to what I put in

Strain/age: 4 haze xl’s from homegrown cannabis co. And 1 UK cheese from growers choice. The plant I am writing about is the UK cheese, although some of the other ones are starting to lighten up now. For one I am using organic nutes from homegrown cannabis co and have no problems. They are 7 1/2 to 9 weeks old. The UK cheese is the youngest.

light used: spider farmer se5000 LED 480watt at 70 %. I am running it 20/4 and it is about 15” from the tops although a couple branches are a little higher, but show no stress from that.

Climate: Temperature is about 75f give or take a couple degrees as it fluctuates. RH is about 55 to 62%

Additional info: The plant has been affected for about a week and has been getting worse pretty fast. There are others starting to get lighter which worries me. Like I said above I have the fox farm trio…but I do not use the grow big. I did think maybe it was nitrogen and was going to give it some grow big yesterday, but decideD not to thinking just plain water might be best. Thank you for all thehelp. If you need to know anything else please ask. Here are some more pictures.

These are autoflowers. Copied and pasted from an auto website as I am not getting any input and the situation is getting worse. Any ideas ? Thank you

Is your runoff pH in range (6.3 to 6.8)? I would expect if using Fox Farm nutes that you are experiencing a salt buildup by this point in the grow. It makes pH difficult to keep in range.


I checked last night after feeding with tiger and big bloom also added grow big this time as I have not used that at all. Going in it was 6.5 coming out 6.1 - almost 6.3 depending on plant, although the EC coming out was pretty much exactly what I put in.

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The EC should be lower in your runoff if they are eating. It looks like they are hungry and are eating themselves to make flowers. Plant will consume all its leaves if it has too. If your ph is good, and ppm is good, but runoff is higher or same then chances are there are challenges with the root zone. Last plants i had that looked like this with correct ph and ppm had root issues.

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Looking at the light green and reading not adding the grow big leads me to think a nitrogen deficiency. Nitrogen is still needed during flower just not at the amount in veg. The FF trio is notorious for salt build up in the root zone and recommend to be flushed every 30 days or so. Watering and feeding to a good amount of run can help expel the un-used salts and minerals that can potentially lock out nutrient uptake. My auto PPMS are 900 in veg and 1000-1100 in flower then I water feed only the last 2 weeks. I would give them a good watering to about 20-30% run off, PH at 6.8 to get that back in a range of 6.5 and check those run off numbers. If less than a 1000, feed with the trio, calmag and some beneficial microbes like recharge :love_you_gesture:


Thanks for the responses. I have one plant I’m giving organic nutes only and have no problems, another one that I’m feeding the fox farm trio that looks great but I did feed that one with grow big once as it was behind the rest so I thought it might benefit it since it was stretching. I have only been giving the nutes about 3 -3 1/2 weeks. Do you think it’s from a build up or not feeding grow big? I water till run off every time I water.

:point_up_2: That’s a good thing. What is your PPMS right now? What medium are you growing in? Issues will take several days to show recovery and the Grow big will be needed for the entire grow minus the last 2 weeks. Mix a gallon of the trio at 1/2 strength and check the PPMS, flowering stage should be around 1000. Check the run off numbers before feeding the above :love_you_gesture:


They were at about 1300 going in and coming out. Adding those 3 at half strength always brings it up over 1000.

Actually when i feed I use 3 liters so I should add some more water or give a little less than half dose

That’s good. 1000-1100 for flowering. Are you in soil or coco?

Ocean forest and happy frog mixed

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Nice, both great cannabis friendly soils :love_you_gesture:

I’m a newbie at this so feel free to take a couple of grains of salt with what I say. But I would absolutely agree with at @OGIncognito because he’s always led me down the correct path. Mine were doing the same thing and I had to adjust the ppm. She was very hungry and I was only feeding half strength because I was so terrified of nutrient burn. Are the leaves up close looking like this?

I instituted a little higher ppms like the more experienced growmies above are telling you and I also varied my pH with each feeding between 6.2 to 6.8 which helped take up some nutrients she was lacking like phosphorus. I also fed 4 cups or 500 ml of dechlorinated and 6.5 pH clear water between feeding days to rid the salts.Good luck and keep us posted on how you’re doing.


Good stuff Brother :love_you_gesture:

Thanks for the input. The leaves on my plant look similar but a little different. They have a lot more brown spots. A couple of my other plants are also starting to lighten up. Hopefully the addition of the grow big will help. I hope. Usually in between feeds I water with molasses. Do you think I should give a little bit more of grow big with it or just wait till the next feed.

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@Never_Legendary How did your plant finish out?

Not sure on that one. I’m using a nutrient line that is a 3 parter because I didn’t know what the heck i was doing with all those bottles of different funny names. I decided to stick with the basic nutrients and feed full strength at regular intervals with smaller water only feedings between. That solved my problem.

I also read that doing too much molasses will cause an explosion of the microbes in the soil and might knock stuff off balance. But again, I read that, I don’t know how true it is. I’ll see if I can find the post and link it to you. Is your molasses unsulphered? I hate to add one more thing to never ending list of things to worry about but I know sulphur is ultra hard on the roots. Or so Kyle Kushman says. :rofl: