I grow my plant plant in a Waterfarm and I just use 2 60 watt CFL's until the plant hits 6" tall. Then, I turn on the HPS and continue to veg it until it's 12" tall, then go into flowering. And because hydro grows the plant fast, this only take a week or 2, tops to get the plant from 6" to 12".

It saves my ass on electric costs and keeps the entire growth cycle to a minimum, at any rate. Shorter growth cycle, more harvests per year!