I use 48" shop lights from one of the big box stores. I have some metro shelving, with fixtures above each shelf. You need as much light as possible on most plants to keep them going indoors. You need to maximize the amount of plant surface that's exposed to light. You don't say what kind of plants you have - large, like a schifflera, or smaller like violets or small orchids? A lot of plants need to have the light no more than a few inches above them.