They're not doing so great... first time grower, long time listener.

Your plants are all suffering from an Mg shortage; whether it's because of your pH or because you're not supplying it (Mg) adequately enough. You're under an LED which exasperates the plant's need for Mg. If it were me, while I'm trying to figure out my pH; spray them with Epsom Salt. Once you get a handle on your pH, start making Mg a part of your daily feed. Good luck.

When you initially transplanted did you remove the 3" jiffy pots? Figured I'd ask just in case.

yep, the jiffy pots peeled right off.

CannaCountry said:

Your plants are all suffering from an Mg shortage; whether it's because of your pH or because you're not supplying it (Mg) adequately enough. You're under an LED which exasperates the plant's need for Mg. If it were me, while I'm trying to figure out my pH; spray them with Epsom Salt. Once you get a handle on your pH, start making Mg a part of your daily feed. Good luck.

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Epsom salt > calmag? I have both handy, so either works. Unless it has to be agricultural grade epsom salt. I just have Target brand epsom salt...? And foliar feed with epsom salt, correct? 1-2x a week?

Also, @Dontjudgeme I didn't realize I have to leave the water sit! Well, I'll start implementing all these changes henceforth.

Epsom salt is magnesium and sulfur.

It is said that the plants need calcium and magnesium and all the elements is a specific RATIO. If the ratio is not right then it doesn’t work. You could spend some time to figure what that ratio is. That’s why some nutrients are ‘specifically made for cannabis’

I think it needs more calcium than magnesium , and I have seen the numbers 5:1. But I’m not sure.

Looks like light stress to me.
Slow light burn.

Maybe up your temps to 82f and get your vpd in order.

I don't see any info on light distance, hours of light per day which would be useful.


Im not saying you don't have other nutrient issues going on though, simply a stressed light burned plant isn't going to uptake properly and leads to more problems.

When you have a plant that show what looks like mag def but worse higher up than lower down then you have to start looking at light burn/stress. which looks similar but starts at the top, though slow light burn can start on older leaves because they've been overexposed in less than optimal conditions for longer but at a lesser level.

https://www.growweedeasy.com/cannabis-plant-problems/magnesium-deficiency


you have to start looking at the space and say well is one worse than the other with all other variables been the same, are the outer most plants doing better, greener , the inner plants looking sad, droopy, red veins , yellow leaves...

It does not need to be Agriculture grade Epsom...what you have will work.

CalMag has both Ca and Mg, generally along with Fe and N....I prefer to give the plant what it needs, vs. what it doesn't, but if it's all you have or you just prefer to use it; by all means use it.

Yes, then go ahead and spray them, once or twice, but this is just a band aid, you will need to fix the underlying issue, which I believe is your pH.

I would however, also heed what @coreywebster is saying; be sure your lights aren't too close.

Good luck.

SnidleyBluntash said:

Epsom salt is magnesium and sulfur.

It is said that the plants need calcium and magnesium and all the elements is a specific RATIO. If the ratio is not right then it doesn’t work. You could spend some time to figure what that ratio is. That’s why some nutrients are ‘specifically made for cannabis’

I think it needs more calcium than magnesium , and I have seen the numbers 5:1. But I’m not sure.

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In the root zone this is correct, mulders chart. but foliar it doesn't apply, Epsom gives a faster uptake of magnesium with a foliar spray.

I only bring up the light stress because its LED and ive seen it in my own grows, always happy to be wrong but best to consider all possibilities.

Certainly not discounting anything anyone else says because they know their stuff.

coreywebster said:

I only bring up the light stress because its LED and ive seen it in my own grows, always happy to be wrong but best to consider all possibilities.

Certainly not discounting anything anyone else says because they know their stuff.

Click to expand...

And I don't run LED's which is why it's important for the OP to listen to what you're suggesting; I have zero experience with that particular issue. Anyhow, good stuff.

Yeah, so my lights have been a steady 2-2.5 feet away from the plants. I'm using Meanwell drivers and pulling ~640w from the wall. I don't have a dimmer, so it has been full blast since the beginning. I was also running 24/0 cycle. I dropped that down to 16/8 two nights ago. However, it is definitely WAY worse lower down on the plant; my pictures just suck. /: The top/new growth looks decent, but a bit neon in color. Whats interesting is I have 1 plant that looks perfect. Same nutrients, same watering schedule, same room, same genetics.... and I have another one that looks like a mutant bush of some sort. If I spotted it in the wild, I probably wouldn't even know it was cannabis. Guess a different pheno? Either way, I do believe the problems are worse lower down and on older growth.

I'm going to use epsom salt in a foliar feed today. "1 tablespoon per 5 litres of water" Does that sound about right? I also have GH CalMag available. Is it worth doing both a foliar feed and adding CalMag to my waterings once a week? How long will it be before the plants "tell me" that it is working? I'm not impatient, but I do want to be aware of timelines so I don't fuck this up further.

I've been adjusting pH (using GH pH down) to ~6.2. Is there still a possibility this is a pH issue? I actually emailed Fox Farm about this when I first started pHing the tap water and that was their guidance. However, I never let the water sit for 24-48 hours before pHing and watering. I'll do that from now on.

Also, most importantly, I really appreciate everyone helping out here... I know a lot of this stuff is documented across multiple resources (books, websites, threads, etc) but the ability to put all of that information together into a sort of tribal knowledge is extremely helpful. THANK YOU ALL!

If Mg is what they want, the foliar feed will green them up within just a few days...again, spraying it is just a temporary fix. You'll need to get a handle on your pH and work Mg into your feed schedule. When you start working the Mg into your feed, stop spraying it...you don't need to over load the plant. I use 1g of Epsom per gallon, however, I run coco / hydro, for what it's worth. Good luck

What exact tools and containers and measuring devices do you use to pH? Like how big of a batch of water are you making at once?

I fill either a 5 gallon or 2 gallon bucket with tap water. Wait about thirty minute. Test with a (recently referenced) Vivosun pH pen. Add a tiny drop of General Hydroponics pH down, remeasure. Come back in 30 minutes, measure again. If it is between 6-6.5 I consider it good.
Does that help?

Ok very good response. well you have to stir the solution. If it was me, I put the acid drops in FIRST, and then add water, this STIRS the solution fully, and pH measuring is ready right away. If you let it sit and not stir the acid will not necessarily mix completely.

I think pH is the issue, and I think you should try to add a known amount that you have been using, add the drops first, then add water and boom done, measure the pH. See how that works out. if you have a lot of pH down you could even practice so you know exactly how many drops to put for your container. for me I put one squirt of my dropper for my container I fill with, after a while I dont have to use the pH pen every time because I know I will be close enough

Good call on the experimentation. Anything I can do to remove the guess work is a plus. I know anything more than a drop or two is a problem and I'll need to add more water to dilute and bring the pH back up. I've made that mistake before. I'll start adding the pH down before the actual water. I really like this idea.

I forgot to mention that I use a garden sprayer pump to "mix" the water while adjusting pH.


I'm not sure if it helps. It just agitates the water a bit. It definitely isn't creating any significant movement in the water. Just some bubbles and ripples.

In other news, the low strength feeding I did yesterday seemed to help a bit. The leaves didn't look so sad today. I did a foliar Epsom salt feed earlier this evening. Probably about 90 minutes before the lights went out. Used 1 tablespoon per gallon.

I'll post updated pictures tomorrow.

Ok if 1 or 2 drops is your margins then I suggest you make an additional batch of water and acid, and create a weaker pH down solution, that way you can have more fine adjustment. You could say, add 10 drops to a gallon, and that water will have a very low pH, lets say 4.0, then use THAT solution to add to your final solution. You might have to add 15 drops from that, and thats better than 1-2 drops

Roger that. I have an ample supply of empty sanitized 5g buckets. Start with x drops of the 4.0 water and add tap until I hit ~6.2. seems reasonable.

They do look a little sickly...lol. But all salvageable. Never give up on your plants. It will just make you better, I would do the last transplant. Buy a saucers for each plant.
I believe the mix of dirt you are using is ph'd balance.(please read the bags) But i do know HAppy frog has dolomite lime. which helps balance ph
1. transplant with the same mix adding different types of bacteria to the root ball
2. add some happy frog fruit and tomato. you can use about 30ml per gallon. this is a easy amendment to the soil. it will probably satisfy all of your nutrient needs, except for the calmg. it has alot of bacteria
3 Add epsom salt and crab shell to your mix, about a cup of each for every pot (calmg)
4. remove the dead or dying leaves
5. watch but do not touch
6. bottom feed ergo the saucers. This will allow the soil to become moist and not wet. you do have leaf curl if the soil is moist enough it will not absorb the water. If it is dry enough the water will be gone in a matter of a hour. Then you can gage the weight of the pot by lifting it.
Also stop phing your water, let the dolomite and bacteria do the work
Another reason I say this is because if the dolomite is in the Happy Frog you are fighting against it. Feed the bacteria. They will balance everything for you