I've heard they can fit just fine in an incandescent hood. Plants like a spectrum between 5000k and 7000k. I personally use and have had the best results with 6500k bulbs, they're the GE brand, called 'daylight' bulbs. The kelvin rating is on the back of the box. They're around $7 for a 3 pack. :D
Check under your hood. Mine had standard (I believe they were 15 watt) incandescent lighting. I replaced them with two blue daylight 15 watt plant bulbs with no damage to the hood, and some very happy plants.