Brown leaf spots due to pH problems?

My otherwise healthy plant started getting big brown spots on some of its leaves just within the fast 2 days. I’m not feeding it any nutrients, and have it in Fox Farm ocean forest soil.

Could it be pH? What is the best way to check the pH of the soil?

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You can do a slurry test for the soil or check the runoff. Slurry test just take some of the soil and pH neutral water (distilled) put both into cup and measure the slurry with pH meter.

you can check your run off. Give your plant enough ph’d water to get about a 15 % run off and check the ph . It should be representative of ph at your roots

You’ve got a potassium deficiency probably caused by bad Ph, or not feeding any nutes. Find out your Ph and we can figure out which.


@raustin is on point. Im with her, potassium deficiency


Thanks for the input everyone!! The run off pH is around 6.5-7.0, so it looks to be good. Hopefully some nutes will get her back into good shape!!

Ok, what do you mean by “around 6.5-7.0”? 6.5 is good, 7.0 is too high, so you need to be more accurate on your Ph. What are you using to test?

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Looks like bugs to me :bug::spider::spider_web:

It’s a magnesium deficiency.

I used litmus paper to test the pH, hence the ballpark rather than a specific reading.

You really should get yourself a Ph meter, it will be much more accurate and you need to be accurate. Here is a cheap Ph meter that will work just fine:


Yes maam, i cant agree more!

Thanks for the link to the pH meter!! @raustin You were right - it was a magnesium/calcium deficiency. I started feeding some CalMag and she’s doing much better now. Some people at the Rollitup forum said that they’ve had problems with the FoxFarms soils being calcium deficient.

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I’m glad it helped, that’s awesome that your plants are back on track.