Plant developing brown spots

Does anyone know what these brown spots could be? It’s only on one plant the top left.

Do you provide magnesium to those plants?

A light green or yellow coloring will begin to show on the veins and edges of the lower & older leaves – this is one of the classic signs of cannabis magnesium deficiency. You may also see red stems.

Magnesium is a mobile nutrient, which means that the plant can move it from old leaves to new leaves.

The edges of the leaves may become yellow or bright green and may start feeling crispy to the touch. This crispiness around the edges is different from nutrient burn, which does not lighten the margins inside the leaves.


Yes I have been giving them calmag but recently lowered the dose from 5 ml to 2 ml due to the flip to flowering. I was attempting to make ppm room for potassium and phosphorus. It’s the second week of flower

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This might help you troubleshoot. If you’re on mobile, scroll down to he bottom to sort by multiple symptoms. Troubleshoot Plant Issues | Problem Identifier | Trifecta


Thanks for the information. I figured out what the problem was with some help from a moderator PurpNGold74. Turns out 90% intensity was to intense for that plant. The other plants showed other symptoms of light stress. Like tips yellowing and curling.

That’ll prevent heat stress, bleaching and fox tailing but you still have a deficiency showing in your leaves. I leaning towards calcium which is usually accompanied with magnesium. What’s your PH? Calmag is taking in starting around 6.2-6.5. If your run off PH is less than that, could be the issue. If you’re PH is good I would suggest supplementing calmag :love_you_gesture:

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This was my last reservoir change on October, 19th
Changed reservoir 40 gallons of water 220 ppm, 200 ml Tree Trunk 50 ppm, 200 ml CaIMag 370 ppm, 360 ml part A 750 ppm, 360 ml part B 260
ppm, 40 ml Plant Enzmes 0 ppm. 200 ml Sweet & Sticky 0 ppm, 10 tsp Flower Fuel 160 ppm, 200 ml Golden Tree 70 ppm, 20 ml Orca 0 ppm
1880 ppm

Ppm was way to high so this is how I corrected it.
Drained 40 gallons of solution and added 50 gallons of water. Leaving the ppm at 1030

That was start of week one Flower. I’m currently 3 days into week 2. After reading you and MH47 suggestion I added 40 ml of CalMag to the reservoir which was at 980 ppm with a ph of 6.0. After adding CalMag ppm sits at 1080 with a ph of 5.9

Temps lights on 78-80F lights off 75-77F
Rh 55-58% running dehumidifier

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That is dialed in my man, well done. I’m sure that PH will creep up a little but should be still within the range. If you ever want to raise your PH, Silica is a great supplement and great to raise your PH.

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I can believe that. My tap water is at 7.1 ph after adding Tree Trunk (silica) it raised it to 8.4. The calmag brought it down a bit. Thanks for the advise. If you want to follow the progress of the grow and check out the previous updates. Take a look at my Zkittles grow journey

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