Purple?

One of my branches leafs has turned purple, and some of the bud. I dont know the strain. I was going to harvest tonight, but should I wait n see if rest of plant turnes purple? I have had it in 3 days of darkness... What to do??!!

Scratch the Darkness off your list, It's just a myth.
put it back in 12/12, and give her some colder temps.
Don't be scared to give her some cold temps. I had my flower room down to 19F one morning.
It's the period of cold that kills your plants.
Look at your Trichromes. Is it time to Harvest? always go by the Trichromes.

Good Luck on Your Grow.