Leaves curling 34 days into flower

First off this is only my second grow so I'm still learning. All 6 of these plants are clones from the local dispensary. 2 - Sour Grape 2 - Shammy 1 - Skywalker 1- Master Purp. They are on Fox farm Big Bloom and Tiger Bloom every other watering. Ph on the soil is 6.5, temps are 75 in the day and no lower than 60 at night.

The only plant that seems to be having problems is one of the Sour Grapes. Quite a few of the Bud sites have curling leaves on them? Any idea of why there doin this? Also why would it only be happening to one of the plants? thanks

I had canoeing like that when I had some airflow issues that were causing too much airflow on the leaves (they curl up to try to conserve/collect water I think)

ahh really.. never thought of that. I do have a fan on them all day long during the day for extra circulation. I'll try killin it see if it helps. How come it would only be affecting the one plant though?

Any other Ideas?

dont kill your fan for too long it looks from the pics as if the leaves are clawing downwards, I've got a super lemon haze that is doing that right now coupled with early fading, and I have other slh's thriving. What are you growing in (pro-mix, fox farm etc) and have you checked your soil ph on the sour grapes in comparison to the others? Whats the humidity in your room? Low humidity can cause a downwards clawing .

I have had a plant and many of it's cuttings that does that if it's just a tad too close to the light. Doesnt seem to burn or hurt the plant or the flowers, the leaves just hook down. If I back the lights off a couple inches, the leaves go back to normal after a few of days. I've never had alot of airflow on them so thats not the cause for me.

Springtucky:
I am growing in Happy Frog soil. I have checked the soil Ph of all the plants 2 weeks ago and they were all around 6.5 - 6. I will check again this weekend when i water them again. Now the humidity in the room is a mystery to me. I have not bought myself a gauge.. I will invest in one.. I've known for a bit I should get one but haven't looked them up yet. I'm sure its low because i have a lot of ventilation in the room.

Elfroggo:
I am only using a 400W HPS set up and the way the light is right now I have a good 18" of space between the plants and the lighting fixture.

The ph seems right. You should be able to find a reliable temp/humidity guage at your local department store for cheap. Ventilation is a good thing, I dont think it affects the moisture in the air though, so this is a good thing to check. Let us know how things are looking.

I'm a newbie myself but from the reading I've done I'd also look into your nutrients. I always thought "claw leaves" were mainly caused by heat stress or nutrient salts build-up. You mentioned the type of nutrients but not how you were feeding them. Did you raise your nutrients recently? You can compare your water run-off to the other plants if you have some sort of meter. That one plant might have held more salts in the soil. you could flush your soil with just water then refeed them if that was the case. Just a different idea but like I said I'm new myself so look into anything I said before you do it. And good luck

FarmerGee is very correct to suggest looking into this as well, you will typically encounter burn also, which by now will definitely be showing up on your fan leaves especially. I use fox farm nutes (will be going to subcool's organic supersoil recipe, Im waiting for it to finish 'cooking' now) and if you are going by the label strength then they will probably get burned. I use the solubles also (Open Seaseme, Beastie Bloomz and Cha Ching) and right about half strength and my EC is still higher than what I like, and depending on the strain but Ive gotten burn from it as well. But keep us posted.