Pests and nutrient problems on marijuana


A question from a fellow grower:

I have a problem with my garden and I hope that you can help me. I have been growing now for about a year. I was having a nice crop when everything started going wrong. My soil ph is 6.5 and my water is about 6.8. I do not know a lot about fertalizer so I use liquid miragrow as directed on bottle. I water about every 5 days. I am growing in 5 gallon pots. My problem is the leaves are starting to turn brown. It starts on the edges and eventually turns totally brown. I have some pictures. I hope this is enough information and that you can help me.


s is a stretch. 1st off. Miracle Grow is not formulated for Marijuana plants. Get some Foxfarm or something meant for what you are growing.

Now, I usually leave these for someone with better eyesight, but I will give a couple opinions. To start off with:

1st pik. Looks like over watering, or lack of nitrogen. Honestly; these look like different plants, because you have a wide varity of issues.

The 2 in between; I would have to get out my deficiency charts, and I am not sure where they are. We have a post somewhere in the forum pertaining to nutrients mobiles. and deficiencies. 3rd pik could be spider mites or from a foliar application gone wrong.

The last pik looks like a PH imbalance due to the twisted leaves. This can also be the look of nutrient lock.

I am sure MacGyver_Stoner will have a couple good suggestions for you. Peace


It looks like nutrient burn from nutrient salt build up, to me.

I assume you are using 12-4-8 Liquid All Purpose plant Food, or maybe 8-7-6 Liquid Miracle Gro Plant Food Drops. Either way these are really high in nitrogen and should not be used for the entire grow. Cactus plant drops 2-7-7, or their tomato plant food 18-18-21 have better NPK ratios to what cannabis needs.

You can use miracle gro but then you do risk running into problems easier, they use a lot of a type of nitrogen that can cause overly acidic conditions and pH will certainly be harder to keep stable in some instances.

You should probably be watching your nutrient salt concentrations in your soil or in the run off. You likely have an over abundance of nitrogen salts built up, along with potentially a lot of other mineral salt build up – that could very well be contributing to this problem. You can check the run off of your soil with EC/TDS/PPM meter. You can buy these easily enough on e-bay, amazon, etc. Or you can get a simple soil probe “spike/rod” kinda thing, that does more than just moisture and pH readings. One that measures nutrient concentration or “Soil Fertility” Something like this:

In the meantime flush the soil with 3 times its volume of water and then feed using the cactus drops as per directions on the bottle or use the tomato plant food at one tsp. per gallon, if you don’t have easy access to a better balanced nutrient system, or better yet use our Marijuana Booster nutrients.


Oh yeah, probably give plain water only every other watering. This will help keep salt build up low by kinda over watering the soil on the water only day to flush out excess salts. And be sure to let the soil nearly totally dry out by the feel of the weight of the plant and its container before watering again.