you shouldnt need additional lighting. about the only time you would need additional lighting in a greenhouse would be to extend the light hours, in the case of cannabis that would be used to keep it in a veg state if you did not want the plants to flower. would probably only be needed in your case in the winter or very early spring when the days was less than 13 hours.
the reason he is blacking out the greenhouse is so he can go 12/12 in june its a daily process where the green house is covered to provide darkness so the plants will start to flower alot early than they normaly would, its not uncommon to do this in a green house.
bejay Reviewed by bejay on . GREEN HOUSE.. DO I NEED LIGHTS?? BASICLY IM THE UK AND IM GONA BE DOING MY FIRST OUTDOOR GROW THIS YEAR, BUT IM USING POLY TUNNELS. BASICLY WE HAVE A HOT SUMMER PREDICTED BUT THE UK IS NOT EXACTLY CALI SO WILL I STILL NEED SOME HPS SUPLEMENT TO GET GOOD BUDS.. THE OTHER THING IS IM GONA BE BLACKING OUT THE GREEN HOUSES WITH CURTAINS FOR CONTROLLED FLOWERING STARTING IN ABOUT JUNE BUT WILL THE SLIGHTLY LESS RED DAYLIGHT AT THIS TIME OF YEAR BE OK..?? ALSO WOULD PEOPLE ADVISE HYDRO OR SOIL FOR THIS TYPE OF GROW??? PLEASE HELP Rating: 5