Plantmax 24 Watt T5 Fluorescent HO 6,500K Lamp Product Highlights T5 Fluorescent HO Lamps bring you high lumen output. With extreme high efficacy and long life, you can expect great results for plant growth as well as energy savings. Available in both cool (6,500K) and warm (3,000K) temperatures. Operating Position: Horizontal. Average life hours: 20,000.