I am growin 3 plant in my attic, origanal blueburry, white widow and durban poison. When should I start them flouring, Obveosly they cant grow to tall cus there isnt enugh room. How much more will they grow when I change the light hours? Also when I change to 12/12 do I just go from 19 to 12/12 or do I do it gradually. Thanks for the help.