It's probably not 400 watts, thats the equivalent wattage, they are actually probably 26 and 23w bulbs(so like 100 ACTUAL watts). I love CFL's for growing, they're pretty cool...how many plants all together? You are definately gonna wanna increase the amount of light you have in there to avoid stretch, and you will wanna keep the bulbs withing an inch or two of the plants, or as close as you can put them without burning the plants.(put your hand in front of the bulb where the plant is, if it's too hot for your hand it's too hot for the plant)...How about ventilation, any air circulation in there?