Growers House has a large selection of Fluorescent Grow Lights and Compact Fluorescent Grow Lights to suit every gardening need. Fluorescent lighting uses substantially less energy than traditional MH and HPS grow lights. These lights are more commonly used for propagating and mothering plants. T5 High Output (HO) bulbs are the most popular fluorescent bulbs for plant lighting, and they're more efficient than T8 and T12 fluorescent tubes. They are smaller in diameter. In fact, "T" refers to the diameter of the bulb. T12 has a diameter of 12/8", T8 = 8/8", T5 = 5/8". Typically, the more narrow the lamp, the more efficient it will be.