Oh no. CalMag overdose?

I decided to start adding small amounts of calmag to my feedings every few weeks and on my first dosing I spilled a little too much into the pail of water and instead of tossing the water out I said what the heck and watered the plant with it. A couple days later the leaves are turning grey and shriveling up, I flushed some straight water through the soil (Greenfields) and the runoff is coming out urine yellow in color. A quick read leads me to believe I have poisoned the plant with the Calmag. I have started to do a huge flush with gallons and gallons of water and its still coming out yellow.

Is there anything I can do besides learn one heckuva harsh lesson?

What is the grow median

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@hillcrest @latewood @yoshi @Donaldj what are your thoughts

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How much would be a Lil to much mila letters matter

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@garrigan62 What’s Your thoughts

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@FloridaSon you got anything to throw in there

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Unless you spilled a shitload I think you may have other things going on

1st, does the gray stuff wipe off the leaves?

Also when you flood a medium it tends to come out greenish-yellow or urine color, as you put it …we need more information

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unless , you spilled the whole gallon i don’t think its what’s changing your run color … Also how long have they been planted in your soil mix .??? And how much ’ 'estimate " did you over spill ??? can you take photos and post .it’ll help us to help you better… as to flushing … to do a complete flush you need to use 5 X the volume of water as the size of the container “.SOIL that is” one gal container use 5 gal water … 2 gallon =10 gal water flush … BUT if you use " miracle grow soil " itll take ALOT More . I flushed 5 gal buckets twice and still get a run off of 5.9 … and ive been feeding them a ph of 8.0- 8.9 and the run off is 5.9… MJ DONT like M G soil … yellow leaves Purple Stems . let me know what your situation is . will help if can … i mainly hydro these days …

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your soil when rinsed will always change water colour much like tea

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2.5 ml of cal-mag is all I used in a gallon of ph water and with nutrients when I water or feed , but I only grow in 3-5 gallon pots and a gallon is how I feed , hope this make sense of help ?

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Many thanks for all the comments so far. I was whooped and crashed out early last night.
I am growing in new soil, using the Greenfields mixture I got at Worms Way. I have been using Slacker with great success but Worms Way said they no longer carry it in their stores and are selling their stock from the warehouse. I liked the Slacker in that it seemed to dry out quickly so one good watering per week was find. With the Greenfields it seems to hold the water much longer and I can go a good 10 days or so before it seems it needs watering.

As for nutes, I am using the Fox Farm Trio but still seeing slight deficiency in the leaves so I thought perhaps adding CalMag with every other feeding I could avoid deficiency. I opened a new container and when trying to pour into my little measure spoon it spilled out, prolly a couple tablespoons worth. I thought I should dump it but at the time the water was the only “seasoned” water that I had on hand in that it was tap water that had set out for a few days to allow the chlorine, etc to dissipate so I went ahead and used the water.

After the 2nd day many leaves had turned very dry and greyish green, there is still some active green life but most of the big fan leaves have gone bad

I have been flushing the soil with tap water and the PH drops by 1.5 from the bucket to runoff. our local tap water comes out at 8 and my runoff is 6.5 of course regular watering I nute and PH to 5.8 or so and use that but just for the flush I am using tap water.

its looking pretty bad according to the pix but I will keep flushing the 3 gal Smartpot all day and then remove all the dead growth and put it back under the 18hr T5 light.

Anything else I can do? I certainly learned a lesson here that wont be repeated. If I lose the plant it wont devastate me but it would be nice to save this Goldleaf and Jack Herrer.

A couple months ago I broke my leg and when I finally got back into the garden after 4 or 5 days picked up some water that I thought was 8.1 (tap) but I had already pH’ed it at 6.5, by the time I put the nutes in it was probably for 4.5 pH and I damn near killed half my garden ! :frowning:

…most recovered but some never will, so it happens …don’t beat yourself up!

I don’t know if I’d keep flushing it maybe some others can help you there, but I certainly would raise or turn down the lights for a while

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Nutrient Deficiencies In Marijuana Plants: The Ultimate Guide Are you using bottled water to water? usually when I see a plant looking like that it’s root rot or major ph issue but since I haven’t seen the progression of symptoms I will say it wasn’t Cal-mag the colouring makes me think of sulfer or potassium Stop Potassium Deficiencies In Marijuana Plants - Ultimate Guide
Stop Sulfur Deficiencies In Marijuana Plants Now! both of which would be ph related

for feeding I fill up gallon jugs of water and then let them sit uncapped a few days. when I get ready to feed I pour a couple gallons into a big bucket, add nutes and then PH down to an acceptable range.

how often do you check run off ph since you are growing in an organic soil you should have ph close to 6.5 though if your soil is taking up to 10 days to dry I would be concerned with root rot as a suspect myself the tap water you are using well or city and if city do you Know it’s starting ppm sometimes there are things in our tap water that plants don’t like. What’s the ppm/tds of your run off like?


I don’t check it regularly but at least every other feeding.

This problem only occurred after the Calmag was introduced and is only affecting the two plants which got the CalMag feeding. All my other plants are doing fine but are in flowering phase and on different nutes which I didn’t include the calmag there.

then a good flush should help clear it up

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I’m still learning about the different additives as I always used MG and superthrive. So I really can’t offer anything about that part, but I have to agree with the run off coloration.

It’s one of the reasons it is recommended to flush until run off is clear. Probably just a build up of dissolved organic matter. Of course, yellow like pee makes me wonder about ammonia, but I’m not sure ammonia colors urine. Some nitrates are derived from ammonia, though, which is what led me to that thought. Mind you, my logic could be flawlessly flawed! Lol

I really hope it all works out as I’m eager to see the end results!

This is exactly what I was going to say. I would be concerned with medium that does not dry out for 10 days.

ON a sad note. CalMag can damage plants if applied in too strong a solution. Those images look like a severe case of Nutrient lock. 2 TBS is 30ml, and you said that was the over spillage. I use 3-5 ml per gallon, and it is a fact that Calcium and Magnesium in too strong an application can cause this issue.

I do not think you need to look any further than you mistake. I do not think this plant will recover. The only thing that would save it is to re-pot into fresh soil. Good Luck


Late reply but those look like goners bro

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