Calcium and Magnesium Deficiency.....quite the pickle I'm in!

Good morning from sunny Florida cannafam! I’m hoping to obtain a solution to a problem I have put myself into. I have Cherry Pie and Skywalker OG seedlings under an HLG 260XL. They were originally potted in FF Happy Frog in 16oz party cups. On day 5, they began showing symptoms of a pretty bad cal/mag deficiency. On day 8 the leaves were over hanging the edges of the cup by at least an inch and roots were growing out of the drainage holes. At that point, I decided a transplant was in order. Yesterday, which is day 9, I transplanted into 2 gallon nursery pots with a mix of 2 parts happy frog and 1 part ocean forest, and watered them in completely with ph 6.5 RO water. Obviously, I need to remedy this deficiency. The real pickle is that it will be a WHILE before these babies have used up the water in the 2 gallon pots, so adding calmag to the water doesn’t seem like a viable option with the risk of severe overwatering lurking. This is my first indoor grow and, I’ve NEVER had a calmag deficiency using the same soil mix before. I’ve read much about the use of led lighting and calmag deficiencies, but have reached no real conclusion about how to remedy it. Is foliar feeding of a calmag product the only viable solution for me at this point? Thanks in advance friends! @Bulldognuts

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Huh yes I haven’t experienced calmag issues either in fox or at least not yet. I see you tagged Bulldognuts look forward to seeing his opinion.

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Seedlings, in fox farm soil, with a calcium or magnesium deficiency?
Do you have any pics?

Btw- you can’t easily pH RO water, good thing you don’t have to.

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Apparently, led lights are notorious for calmag deficiencies. Their are several schools of thought as to why. Bulldognuts had a similar issue when he switched to LED lighting. I’ve also never experienced growth like this. It’s hydroponic level fast. In a week my seedlings became nearly root bound and the first true leaves were wider than the cup! A WEEK! I’m not sure if the high growth rate consumed all of the calmag available in 16oz of soil or if these nutrients were unavailable to them for some reason. New growth is no longer purpling and the stems have gone mostly green again after the transplant. They are only 3 nodes high. The first true leaves are severely damaged from the deficiency, the three bladed leaves have very very minor signs of a deficiency. I just cant afford to lose the last set of healthy leaves, so I’m pretty much freaking out.

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@Drinkslinger my water comes out of the RO filtration system at 7 and I PH down to 6.5 with PH down, which I believe is citric acid.

RO/ distilled water is pH neutral, it will take on the pH of the media it’s put in. You do not need to adjust the pH unless for a specific purpose.

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I see where this looks like a calcium deficiency.


The spots look like it, but I have a hard time believing the plant is not finding what it needs in fox farm soil right now.
Do you spray/mist your plants under the light?

There’s also a twisting of the leaf. It may be too close to the soil and not liking it.

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I don’t spray or mist the leaves. I am extra cautious about not getting water on them and cooking them. I haven’t even considered the proximity of the leaves to the soil. I’m really at a loss and questioning whether this is a calmag deficiency or something else going on. I tested my runoff for ppm and PH. I am uncertain of the effectiveness of using runoff from soil to determine the amount of nutrients available. In hydro definitely, but there is a bunch of unknown stuff in soil. My runoff ppm is CRAZY high though. Like 2800 ppm! How accurate is testing of soil runoff?

Ok. So I spoke with fox farms on the tele just now. They say that there is enough nutrients in the happy frog product to last for the first 2 to 3 weeks of growth. However, they advised me that because of the ridiculously fast rate in which these girls are growing, they most likely just are all of the available calcium and possibly magnesium in the first week. It’s hard to tell by the pictures, but these children are only 9 days old and larger than my xl glove sized hand. They were nearly root bound at only 6 days!

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I agree that is what it looks like because I have a bottle of CalMag available at all times. However, I would be very surprised if that’s what it is. I don’t associate that deficiency until much later on. I grow in FF OF and just not run into that early. My light is a LED as well. Any chance it is just dried water drops?

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I don’t think so @beardless. I have been meticulous in ensuring that I don’t get water droplets on the leaves. In the rare case that I do get a droplet, it is swabbed away immediately with a sterilized surgical swab. Also, the necrotic spotting didn’t occur until after I had already observed symptoms. Even if I did get a droplet if water in the leaf itself, I don’t think it would cause the leaves to twist and claw the way they have. Also worth notice is that it isn’t just one plant. All nine have shown similar symptoms with varying degrees of severity. If it were a stray water droplet, it wouldn’t have affected the entire crop. Thank you for the insight though!

Meticulous - yes. Sounds like you have it covered especially with multiple plants affected. Your comments made me think about it some more. I looked at some of my notes and pictures and I did run into it with Amnesia Haze autos on day 22.

This should look familiar. CalMag eventually took care of it. Sorry for the incorrect first reply.
You mentioned runoff PPM. I just check the run off on my NL I transplanted into 5 gallon smart pots. This as there 2nd watering, the first being just enough to water them in. It is primarily FF OF with some compost and a brick of coco. The PPM was 2486. My understanding is this is pretty typical for FF soils. FWIW

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@beardless You didn’t give me an incorrect reply, from the photos without any further observation, the spotting could likely have been burns from water drops. Currently, I’m of the opinion that the best course of action is to wait until regularly scheduled watering and implement calmag at that time. The new growth looks healthy so far after the transplant. I was considering foliar feeding calmag after lights out for an immediate remedy. I’m not sure that’s necessary any more.do you have experience with either of these strains?

I didn’t catch the strains. I have grown white widow, blueberry and amnesia haze. All autos. Currently have Jack Herer autos (just seedlings) and northern light photos going.

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Ok friends and family! I hate when a thread is started, but there is never an update. So here goes…I was right AND I was very very wrong at the same time. Indeed the calcium AND magnesium deficiencies were very real. We nailed it on the diagnosis! The new growth was a little yellow for my liking also so I also suspected they needed more nitrogen. I assumed they were just hungry and wanted some food. I resisted the temptation of mixing up a gallon of love potion and dosing them. I foliar fed Calmag to them at 5ml/gallon. NOTHING changed. In fact I began seeing the conditions worsen. After a couple days of calling around and asking for help, nobody had a solution. So what am I to do? I went back to the basics! I ran enough 7.0 RO water through one of the pots to get a testable amount of runoff. How does 5600ppm and 5.4 ph strike you for a soil grow?!? I knew that “super soils” could be a little hot, but damn man! 5600 PPM? I flushed the shit out of the plants using 90 gallons of ro water through 9 2 gallon pots. I am happy to report that not only are they looking FABULOUS after only a few hours, most of them didn’t even droop from this amount of water! Ppm’s are currently sitting at around 500 with a 6.5 ph. Never EVER will I waste money on FF soils again! EVER! lmao

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So your ph was to low and caused a nutrient lockout ?

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The PPMs were through the roof, but I think it was the acidity of the soil mostly. From what I understand, calcium and magnesium are immobile nutrients and aren’t readily taken up by the roots in soil under about 6.1 PH.

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Yes the ph you had locked out cal and mag. The ppm run off is always very high on new soil.

Here is chart for future reference. One sec I have to edit it.

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@BetrayedSoul THIS is golden! Thank you so much for making this tool available to me. I saved it. Will I be battling the acidity for my entire grow? Should I start amending with lime ASAP? I actually chose soil as a medium because of the buffering. I thought it would be less maintenance.