What you don't know your[npk] ?that's is one of the most importent thing bud....If your growing in pro mix [soiless soil] I use 20-20-20 light doses every watering.then when you are ready to flower switch to something like 0-50-30 you don't need nitrogen at this point,you don't want your plant to get taller it is the nitrogen that makes it taller ,you want fat buds ,so try something with the last two [npk]hight.your leaf looks fine that's the cold.you should wait a week ot two before crop time and let the cold get to them ,it will make her cry thc and go purple.