Lights with higher blue spectrums are best for vegging. The ideal range to shoot for is between 14000K - 20000K as they contains more blue which is the most important light spectrum for vegetative growth  .
Color temperature, or degrees Kelvin (°K), is a number assigned to a bulb to describe the color of light it emits. The lower the number the warmer or more to the orange/yellow side of the light spectrum is its appearance. The higher the number the cooler or more to the blue side of the light spectrum.

The bellow diagram shows some °K examples and their corresponding colors:

Tutorial written by Oz Stoner for cannanation.com/ozstoners.com