Grapefruit 1st grow

No nute's to start, FFOF with a 30% perlite mix, watered in to 5gal tall plastic pots...cold dry conditions outside have left me to create more humidity in the room by water pans with soaking towels. Running my 1000watt MH at 50% 24hrs a day 20" from the top of pots. I am guessing but based on research I think that this will lead to more veg growth. I plan to increase strength as plants can handle it, eventually running 1000watt HPS.