New growth leaves are twisting and curling at the tops

I have two plants showing these issues. Here is the album of them both.


Close ups:
These two plants in particular are showing leaf tip curling and twisting on the newer growth.

I had a fan directly pointed at them over the weekend because my house AC died and had to wait two days for the repair. My idea was to get air moving across them. The fan wasn’t on high but it was directly blowing into the canopies of these plants. Started noticing this on Monday, and I’m still seeing signs of this Thursday. The tent temp during the weekend AC fiasco was 89-91f and 70% - 75% RH from Saturday morning to about noon on the following Monday.

Here are the details:

Watered on Saturday with dechlorinated tap water ph’d to 6.55. 4ml of CalMag to 1 gallon added.

Soil is Fox Farms OF with 30% perlite and amended with dolomite lime to buffer the ph.

Soil ph is sitting at 6.3 (last reading taken on Sunday evening). Not sure the accuracy of this digital meter I have but that’s the reading I got from almost every pot. They all have the same soil and water routine up to this point so I can believe it for now.

Temps in the tent are between 77-80f with an average RH of 55%.

New light added this past Saturday. A Maxsisun PB2000 (SF2000 equivalent). I started it at 28in for a couple days to break them in. Moved it down to 24in and it’s currently been that height for the past two days.

Both plants got 3000ml of h20 @ 6.55ph at the last watering with a dose of CalMag. I’ve given CalMag at 3.5ml per gallon every other watering since week 2 and have not seen any issues. Both are 5 gallon containers. Watered them when dry, so not sure if it could be over watering. Haven’t done anything out of the normal routine.

Just wondering if this could of been due to the fan blowing on them so ferociously over the weekend. It’s odd to me that this isn’t isolated to one plant and it’s only showing on new growth, so I’m leaning towards the fan stressing them out.

No leaf discoloration, nothing wilting or dying off. I’m just kinda confused as I’ve had a few out of control variables over the past few days (no ac, fan left blowing directly into them) on top of a watering and adding a new more intense light.

I’m starting to believe this has been caused by the nitrogen in the CalMag. From what I’ve seen around, I’m leaning towards that being the case.
I’m discontinuing CalMag until I’m into flower. I pulled the water report for my city water and it was very low on Calcium so I figured shooting a half dose every other watering would be okay, but that nitrogen is now just sitting in the already hot FFOF. Haven’t had an issue up until this point, but I’m thinking it has built up over time and now the last watering was the peak of the iceberg so-to-speak.

Hey so did you figure out the issue? I just got x4 of the Maxsisun PB2000 lights for my 4x8 tent and I wanted to make sure that it wasn't the lights that caused this. I currently have 8 clones vegging outside in a portable greenhouse and I am planning on bringing them inside to flower with these new lights. Would you advise on hanging them at 24" above their canopy to start? What distance have you settled on for vegging since your post? Have you noticed any light burn?

Little_Yeti said:

Hey so did you figure out the issue? I just got x4 of the Maxsisun PB2000 lights for my 4x8 tent and I wanted to make sure that it wasn't the lights that caused this. I currently have 8 clones vegging outside in a portable greenhouse and I am planning on bringing them inside to flower with these new lights. Would you advise on hanging them at 24" above their canopy to start? What distance have you settled on for vegging since your post? Have you noticed any light burn?

Click to expand...

It manifested as nitrogen toxicity eventually. 99% sure it had nothing to do with the lights and more to do with the weekly CalMag feedings boosting nitrogen levels over time. I’m also in FFOF, so that didn’t help. I’ve got my light sitting 14-18in away from most of the main canopy here in the final few weeks of flower. I have a light meter and base my height on those. Getting 450-750ppfd at the outside edges of the light and around 1k ppfd in the center.

Were you able to solve the issue? How are they looking now? Are the lights good enough to give you solid dense nugs?