you can grow on your windowsill but have some other kind of light on when the sun goes down so you get 18 hours instead of 10 to prevent early flowering. I did this with about 7 hours of sunlight and cfls only during sun down. Ended up with a 4 foot plant but only about 1/2 oz. I would have yielded more but too much nitrogen in the miracle gro soil and the cfls did almost nothing besides tell the plant it is not night time. Hope this helps.