For two plants you best value to make it worthwhile is 4 42w actual cfls. You can put two of them in one large clamp reflector from Lowes with an extender and a Y adapter. You want 3 of them to be 6500k (daylight) and one to be 2700k (soft). That's the basic answer but you need much more info which you get from reading the sticky threads on top of each section.