I've done a lot of reading from a lot of different sources, including that cfl grow sticky before I went ahead with this. That's why I got four 42W cfl bulbs putting out 10,400 lumens about 1.5" from the soil. Walmart doesn't sell light bulbs online so I pulled one and it just says 42W helical. I'll look at the store sometime. I'll investigate that wavelegth thing but fact is fact, and opinions are like assholes.....everybody's got one, and they all stink. Thanks.