Regular lights (incandescent bulbs) give off a light rich in red—but plants need both red and blue rays to grow well. For long-term light use, then, you need to use either fluorescent or high-intensity discharge (HID) lighting. If you use fluorescents, usually using one “cool” bulb and one “warm” bulb works well, although in some cases certain plants will do better under special “full-spectrum” tubes.