I am at my first grow ever. It's a Northern Lights Auto by FastBuds on a southside balcony in climate zone 8b. Today I noticed leaves turning dark/purple. Could this be a gentic reason or related to cold temperatures? I don't think it's a deficiency. It is 6th week of flower.
Some strains are predisposed to turn a hue of purple in late flowering. Temperature can also cause this, it’s possible that during the night it gets pretty cool.
I’ve had some blue jack turn purple on me. As long as it looks healthy I don’t see it posing much of a problem.
cold temps, micro nutrient issues like Molybdenum or just autumn ( finish of life cycle of plant ) fade.
northern lights has no purple trate, so its not genetics .