Google is probably your friend on that count. Not sure if the spectrum has as much to do with flowering as does the intensity.
But, have you considered what the flowers will look like under the light? Say if you go for whites or light blues, a cool light will make them appear crisper, a warm light might bring out reds, yellows, etc.
Just a thought.
I usually opt for daylight tubes. I like the sound of it ;-)

Ultra,

The spectrum has everything to do with plant and flower growth. The cool white contains the blue spectrum which is for leaf growth. The warm white is the red spectrum which is for flowering. I don't know how successful you will be using just one but if I had to choose, it would be the cool white. There can be no flowers without leaf growth first. It sounds like an experiment in the making!

Linda

Thanks, Froeschli and Linda for pointing out factors to consider. I might start with a cool white for leaf growth and switch it out for a warm white after a few weeks. But I have to examine my "overflow area" setup to decide if messing with lights frequently is doable. For my double tube fixtures I've always mixed warm and cool but I am also thinking about growing with daylight tubes.

So, does anyone here grow exclusively with daylight tubes? I've always thought daylight and warm white were the same, but have learned that they aren't (see link below). And I looked at the bulb packagings to confirm. Besides spectrum and intensity (lumens), it seems it would be a good idea to consider color temperature (kelvin). According to the link, warm white is 3000k, cool white is 4100k, and daylight is packaged as either 5000k or 6500k. If natural sunlight is 5000k, wouldn't daylight tubes be the most ideal? Hmmm...

Here is a link that might be useful: Lights for growing plants