The guy at Lowe's should probably stick to operating forklifts and selling ceiling fans. Bulbs don't give out watts, they draw watts from the outlet, watts being a measure of electricity. The reason they get confused about it is because CFL's are marketed almost always as a such and such true wattage bulb which is equivalent to a much higher wattage incandescant bulb. The fact of the matter is even the true wattage of a bulb can be deceptive as well. It's all about the lumens. When you're standing in the light bulb aisle trying to decide which bulb is going to suit your needs, read to see how many lumens it's pumping out. The rule of thumb I practice for a good value for a cfl is try not to pay more than $0.0014 per lumen (that's 14/1000 of a cent per lumen.) Something else I've observed is that the watt to lumen relationship is not a linear one. If a 40 watt cfl gives out 2600
lumens, that's not to say that an 80 watt bulb will give out 5200. It would probably be like 4700-4900. And the price for higher wattage cfl's also increases unproportionally. I've found that 26 watt bulbs seem to be the sweet spot, giving you 1700 lumens
each at around $2.50 each. If you ask me, the best idea is to buy a bunch of those because not only do you get a better lumdollar ratio, but you get a larger number of sources of light which means you get to illuminate a wider degree of angles ensuring that a larger percentage of your plant is receiving direct light.
Anybody feel free to paraphrase that, I know it's a huge chunk of text, sorry.