I stay away from cfl as I have never had anything but bright green plants with no growth under them
sorry no offense..but why are you here in the cfl forum then? To spread the good word of our lord and savior HIDs?
is this bulb useful to me?
try looking for a model number on the base of the bulb somewhere and try to google it..or look up the company that makes them and see what K rating their 3way bulbs have..I would guess there's a good chance that they're all "warm white" or "soft white". btw 3way bulbs are much more pricey then regular cfls, and don't really see an advantage to being able to lower the wattage if you're using them to grow with...I highly doubt their ballasts are as efficient in lumens per watt as a normal cfl ballast is. No matter what the K rating is though, you can veg and bud under it for sure..if it's all you have, use it.
lumens are a measurement of light that humans can see, plant don't actually use lumens exactally, but it's a good rough estimate of how much light you're getting from a bulb. In a cfl grow I'd recommend about 5000 lumens per square foot for veg and 7000-9000 lumens per sq foot for flowering (minimum 5000 for flowering)
but in short..hell yeh grow some weed under that lil fucker.