I feed my plants every watering. I'm using Botanicare Organics so its kind of hard to overnute or cause lock up. When i need an extra boost of nitrogen i use some miracle grow veg food. I also foliar spray. I use a really low dose of my veg food for the foliar spray. The light i have are 68 watt cfls(300 equivalent) ther the biggest i can find at home depot. there contractor bulbs, in the same isle as the other cfl's but alongside the MH bulbs and T-12's and stuff like that. At least that's how it is from where im from. lemme know if his helps. thake it easy.