I found with cfls, the color temp (in kelvin) has a lot to do with growth, speed, and photosynthesis. 2700k is a very red/orange spectrum aka warm. 6500k is a very bright white/blue spectrum aka cool/daylight. I bought a 100 watt 6500k cfl and ran side by side tests with a 100 watt 3200k cfl. (same clone, same soil, temp, rh, light cycle, and same nutes) The plants under the 6500k cfl were dark green, branched out like madd, and very healthy. On the other side, the plants under the 3200k cfl were short, super slow growing, hardly any branches, only had one main top, and not looking sexy at all.
The part that makes me laugh, is the 3200k bulb was designed for plant growth, the 6500k bulb had no info on growing plants at all. lol!!
Another thing to check out is the lumens that are emitted. You can have the same color temp, same watts and have a different lumen output. This will vary between manufacturers!
for veg growth, imo, you want 6500k, with the highest lumen output you can find.
And as "bush lover" said, the closer you have the bulb to the leaves, the higher amount of energy they can soak up.... If a cfl box states..... plant growing.... or any thing like it, I will not buy it from home depot, lowes, walmart...ect. (some cfls at hydro/grow shops do have some awesome cfls that say plant growing on the box and they work great.)
I have used only cfl's for auto flower grows and they turn out wonderful. IME photo period plants have trouble making fat tight buds under cfl's. Some photo-period strains will flower and give you alright bud under cfl's. Other strains will not bud, and if they try, its like a finger nail size bud, with like 20-30 hairs. lol!!
i bought it from home depot. Heres a link 
