lights needed for autofloweirng plants...

Im new to all this. I'm doing my second outdoor grow and about to start an indoor grow. Considering doing an autoflowering plant for time and space reasons. Since the plants are smaller can I use a different type of light that hps or mh?

I do the same, indoor in a walk-in closet. I use a 150 watt HPS. I tried a smaller light and did not have much luck. Could have been that particular plant though, but I got a pretty inexpensive Mini FloraLux. Works great, and not much heat. I just have a small fan on it, and the closet door cracked.

Couple 125w cfl's and have had nothing but great results.