Basically, all you need is a light that provides enough light intensity, in the spectrum plants use, to grow the plants you want. It's as simple as advanced calculus!

Depending how many and what type of plants, you may need anything from a 23 watt CFL to a 400+ watt HID light.

I prefer, if I am using a single outlet and not trying to grow more than a plant or two, a CFL light with a 5000K temp rating. It provides the entire spectrum plants need from germination to the end of their useful life.

Tell us what you want to raise and we can give you better guidelines.

Mike

Thanks for the reply! I have a few different kinds... I have several succulents, Jade (which I suppose you'd count in the same group), Spider Plant, Wandering Jew, Philodendron, English Ivy (which I may have almost killed for the last time), Coleus (ditto), and a Flamingo Lily. The succulents don't seem like they're getting enough light, the rest seem to be ok. I'd also like to get some air plants but I'm not sure how much light they need - I'd like to put it in my bathroom but I'm not sure. I try to pick plants that are supposed to be easy but still have trouble. Then of course I get over zealous and wind up over watering. :) I'm getting better (I think). Growing up my mom had a lot of plants in an East facing bay window and I loved it, I've always loved a house filled with plants. Assuming they're not all half dead.