I'm sure they would be OK for supplemental lighting and such, about as good as any other 27W Fluoro/CFL but its only 27W, with the added cost of the ballast & fixtures you might as well get a 42-65W CFL, I heard from a few experienced growers that the most efficent CFL's are the 42W & 65Watters, however if you can afford them T5's with the right combination of bulbs are the best fluorescent grow lights, especially when used with HID/LED they produce excellent results. Ive also been hearing some really good things about induction/plasma induction lights, quite pricy though. You can get a 68W TCP CFL in 2700K at Home Depot for $15, that's one of the best deals Ive found and they work great, very bright but the bulbs are about three times the size of a normal incandescent bulb.