If you're using florescents it's good to do if you can. That's basically what high intensity growers do when they switch from cool, blue-end MHs to the red/orange spectrum of the HPSs. So it's not necessary, but if you can afford to do it, it'll help a bit... or just add some more warmer spectrum lights in addition to what you're already using. You know what the say, the more light the better, right?