Purple Afghan Kush (organic in soil)

Update: after freaking out yesterday when I found fan leaves with black ends and all curled over I’ve decided to just remove any bad leaves for now and let the plant keep maturing. In reading online and a few books, my analysis is this is a bad phosphorus deficiency causing necrosis. I’m not going to add any nutes and will just let it be. Buds don’t seem to be getting affected but will chop at any sign of this getting into the buds. Trichomes look about 50% clear 50% cloudy. I will keep her going as long as possible but she could see the axe this weekend. The smell is amazin and colours are very cool. MOSt buds have deep purple colours to them. Deficiency is helping out a bit too! My original concerns: Some of the Leaves are going blackish green on the sides and tips. Some are dry and crunchy and others are damp and folded over. I wiped the black / dark green parts on a white clean paper towel and there was no residue on the paper afterwards. I also looked with my scope and it didn’t look like any spongy growth on the leaves but I don’t often look at leaves at 120x. I clipped all the curled up leaves off. I will see how it looks and if more leaves are badly affected I will chop 10 - 15 days early or keep it going as long as I can. I’m thinking maybe this is leaves dying off because of cold nights (17 degrees). Any insite is much appreciated. Cheers.