Cant figure out whats wrong with this one...

This is the only one turning purple. I believe its grape diesel. its in some sort of MG soil, I revieved it that way. I gave it a low dose of 15-30-15 food, as well as all my other plants. All the others are fine, even the others in the same soil. Any idea whats wrong? its turned more purple today, but its mainly on the older leaves.

I'll post an updated pic in a bit

True Purple phenos can start very young..... I've seen this in the first week. Looks like it's gonna be nice purple bitch. Make clones of her if she grows healthy.

probably the strain. my purple kush turns purple very early at times. possible K deficiency but the others are fine so im thinking the strain.

Might be sensitive to low temps

Thanks for the help, I didnt think of low temps either. Ill move it back to the warmer cabinet. The others seem to be doing great so maybe this strain just cant handle it. +rep for the quick help! I plan on keeping this one indoors and cloning like crazy! Idk if I can get my hands on more of these clones for next year so this is my baby!