yes.. the plants should be kept in the dark for 12 hours a day minimum...The plant produces a chemical that causes flowering/BUDS when they are kept in the dark for 12 hours. If you leave them outside... and you live in the Northern Hemisphere you should be fine.. WINTER is coming!!!!!! : )

Plants do their best at about 70 degrees faren.. So if you live somewhere and winter is already on yah, you better consider moving your plants into a dark closet at night. Light on a window sill is probably not gonna be enugh to get good buds. So they should be outside completely during the day.

I assume you are keeping this very simple but, You may also want to give your plant some NITROGEN fert - or some sort of 10-10-10 fert.... good luck