Slight leaf curl

[4d-Rock]

Hey All!
I'm growing a White widow Auto from CKS while trying out MegaCrop as a change from Fox Farms. It has been going quite well, actually, it is farther along at its current age then any other seedling I've grown so far. But two days ago it started getting slight curling up at the edges. I've read that it is usually due to heat/light/humidity stress which was confusing to me because I thought I had it in a pretty good zone, 27C/55%RH, and reasonable air movement. My Roleadro Cob light was around 26-28" above it. Since then I have raised the light as much as possible to 30" above and moved the plant to the corner so it isn't directly under the light. This brought the climate to about 25C/45-50% RH. The leaves are curling a bit more as you can see in the picture and also a bit of slight 'tacoing' started to develop yesterday.

Should I just stay the course with the current setup or should I look into other causes and try something else?

Much appreciated!

-Problem: Serrated edges of leaves curling up slightly, also possibly starting to 'taco' a bit
-Medium/grow method: Pro-mix HP Mycorrhizae in 2gal fabric pot. Used the 'easy transplant solo cup' method
-Feed and supplements used: Soil pre-charged with weak Mega Crop at 2g/gal, and 1ml/L Calimagic. Watered ~250mL of similar feed when transplanted on Day 7 and again with 500mL on day 10. All ph'd to 6-6.5
-Water source: Lake water filtered with charcoal/UV filters. ~70ppm/7.3pH
-Strain and age: White widow Auto from CKS, day 11
-Climate: 27C/55%RH throughout, dropped to 25C/45-50%RH after curling, 6" fan blowing on wall to keep air moving around. seedlings move slightly but not too much.
- Light used: Roleadro 400w COB light on 24/7, was underneath at 26-28" when started
-Additional info: It has been 2 days since it started slightly curling up. Slowly getting worse with the leaves showing a bit of 'tacoing'.

--Pictures:

 

[LittleMT]

I can tell you I see this leaf curl all the time in my grows under LED's though I rarely see it outdoors under the sun. Something in the LED spectrum that annoys the plant slightly, in the end it wont matter, in my indoor grows I just let the plant be, maybe like you did, raise the lights or lower the light intensity, as intense light really isn't need in veg like it is in flower. I think you plant will be fine, the bigger it grows the less the leaf curl will be a issue, mine seem to grow out of it. I typically only see it in seedlings and young juveniles...

 

[LittleMT]

In this image, my Inzane in the Membrane seedling was getting this leaf curl from the Optic 2 cobs.

Now here she is today.

 

[Arthur]

The little bit of curl I see is probably just the rH being a bit low. Seedlings really like humidity. Your root system isn't developed enough yet to keep the transpiration rate up.. maybe hang a wet towel in the tent to get up closer to 70%.

 

[4d-Rock]

Cool, thanks @LittleMT and @Arthur

I thought I read pH the first read through, And the last feed was a bit on the lower end than usual,5.9-6. Not sure if that can have any implications on leaf curl, but I’ll bring it back up to 6.2ish next feed.

And I could try increasing the RH too. I have a humidifier with humidistat in there so it’s pretty easy for me to control that.

 

[4d-Rock]

Here it is tonight, hasn’t gotten better, raised RH to 60% so we’ll see how it goes.

 

[LittleMT]

When I see this on my plants, the curl that occurs never gets better and is always there, however it goes away on the new growth and as the new growth occurs it quits happening, but where it has already happened it wont better itself. Now I have never adjusted RH for this, this does make sense so it will be interesting to see how this effects the seedling.

 

[4d-Rock]

Gotcha, makes sense. Similar to burnt tips or other affected leaves from deficiencies. Once the leaf is damaged, all you can do is correct the issue and make sure the new stuff is healthy. In this case it's fairly minor so far so I'm not worried too much. I just want to keep things in the right zone to promote new growth and not stunt the plant further. Still trying to grow a seedling well enough to be able to try topping. But i've never had one be at 4 nodes by day 15-20 to be able to attempt it.

 

[4d-Rock]

Well, the curling has continued with the new growth, but It is still growing at an ok pace. Current conditions are about 25C and 60-65%RH with the lights ~24” above.

Here’s a pic from Day 15

Currently feeding on every watering. Last one was about 460ppm of MegaCrop 2.0

 

[LittleMT]

Looks good to me, this leaf curl IMO doesn't stunt a plant, as I have had 100's explode with growth with this condition in various degrees.