Help - Curling Leaves

[Ardek]

Hello all; I'm looking for some advice on my current grow. To some degree, I've been experiencing this the entire time during my grow, but for a couple plants now it seems to be more significant.

My girls Genetics are Mandarin Haze (4 plants) and Gipsy Haze (4 plants) - issues is happening largely with one of each.
They are into the beginning of week 5 of flower; overall, they look beautiful!

Set up:
5x5 tent, 4200 CMH light, Soil (Foxfarm - Happy Frog)
pH is good, so i know it's not lock-out, run off is testing between 6.2-6.7
RH is good, at about 35-50% (depending if its watering day)
Temp is good, steady at avg of 72 day/65 dark
PPMs (overall) are ok, but run off it testing a bit low (between 550-650).
Watering is also good, so they are generally not over or under watered.
There are no pests present (I've checked close visually and under 100x micro)

So, I'm seeing signs of leaf 'curling' .. It seems that it's probably N tox, but I had that last crop and it was only on the ends of the leaves; this is different over the hole leaf.

I have done much searching on 'plant problems' but usually come to only find under/over watering as the cause for my symptoms, but again, I'm 99.99999% sure it's not that.

I'm looking to get advice on nute deficiencies or toxicities.. Do I need more Cow Bell (Cal/Mag) or am I missing something else nute wise??

I know one thing, I very much do NOT like Foxfarm soil and will NEVER use it again. I was much happier with a generic organic soil last crop, and feel that may be my issue here (something in the soil); but I'm trying to identify what specific nute(s) are either lacking or I have an abundance of to learn for the future when I see this.

[dphipps1020]

So to me it looks like heat stress but if your temps are around 72, that shouldn't be an issue. I'm still fairly new to growing so I could definitely be wrong. Also, I've been using a FF blend of the Happy Frog and Ocean Forest with no added nutrients as my base soil and it's been great for me so far. I actually had a lady that wanted to keep flowering no matter how much light I gave her. She wasn't in her final pot with the amended soil like all the rest but I have a co-worker who used to grow and said that blend should have just about everything to get through a full grow. Needless to say I went ahead and tested the theory since she seemed to want to flower so badly. I must say I'm surprised at how it's going so far. She's not quite a foot tall (was already short when I switched her) but is fattening up nicely and only have a little longer to go. Hoping for at least a half to 3/4 oz out of her 5" branches. Definitely a beast for as little as she is! Here's some pictures too, just over a week ago. She's getting the yellowing leaves from normal ripening/aging, but otherwise still has a nice green color, lots of trichomes, etc. Not sure if that helps at all but I figured I'd share my experience with FF at least.

[OlderNOTwiser]

I'm using straight FFOF and the nutrient trio. Not a ton of experience but your leaves look eerily familiar to me. My first grow showed very dark green leaves and what I saw as the nitrogen claw. They never got any worse. How long have they been in the soil? Are you adding nutrients?

[Ardek]

I add half the recommended nutes, every other water.. so honestly they are not getting much. This next water, I will switch them over to full flower nutes/zero N.

I'm leaning towards the soil being initially too high in N, and any extra nutes I added gave them N tox. Also thinking they are a bit low in cal/mag.

[5Chord]

That rich green color shows that your girl is getting a bit too much N, but is the curling happening to just a few leaves or the whole plant?

[Ardek]

Yea, that's the same thought I had.. Just more of a N tox than I had my first crop.

[Ardek]

I have to say, it would help If I had a proper pH meter..

Comes to find, I purchased a second pH meter a few weeks back. I calibrated it finally today, looks like my other meter was .9+. So while I thought my girls were in good pH, they were a bit low. Not by much, but for most of the grow they've been around 6.0 or lower, like 5.8-6.0.

I added some cow-bell today, and got my pH a bit higher. I also made sure my water temp was at 72-77F. I had been watering with my water temp at about 63F, and that was always causing them to have a short but immediate shock they'd go through. They didn't have that response this water at all, so making a couple changes.

We'll see how they do in the next week.