Looks like it could be wind burn. Something similar happened to a sprout of mine but it was an indoor. Went back to normal when I turned my fan to low Sent from my iPhone using Grasscity Forum
Thanks for the reply. Only thing is I don’t have air blowing directly onto the plants. Could it be some kind of nutrient lockout?
Looks to me as heat issues, seedlings and clones like cooler temps to start. I keep my smaller stuff under 28w 4 bulb t5 about 3 in away until plants are at least a foot tall, ive seen very similar issues when I put clones right into flower for the first week under HID lighting. Even higher draw LEDs still put out significant heat to the plants with light radiation. Also could be a RH issue, is your RH low? Say 40% or lower. Right now I'm having this issue indoors due to cold temps outside. Basement seems to dry right up as soon as fall comes. Ive seen my RH as low as 21% and it causes curling and drying if fan leaf.
Been growing less than a year, so take this for what it's worth. Had a couple nice wins, and more than a couple inglorious failures so far. Girls look pretty overwatered, unless they were *just* watered before the pics and recovered a few minutes later The curled down leaves look like overwatering. The leaves probably feel kind of thick and stiff from too high turgor, its like the plant being forced to flex. I recognize it because I have overwatered in soil pretty much every plant I grew in soil. The turned up leaf tips look like a bit of heat or wind or light stress. This looks familiar to me because my veg/mom area hit 87 degrees F the other day, and a couple of the less vigorous clones started doing exactly that. Have also seem leaves too close to the lights do the same thing. The light color of the leaves look like a bit of N deficiency maybe. In coco, I would say those spots are Calcium deficiency, but in soil, it could just be that the overwatering is clogging the works, and that is why multiple deficiencies are setting in.
Might be over watered but a little more data may help, what's your water PH and how often do you water? What light are you using and what height is it at above the plants?