I prefer to use 6500K (daylight) bulbs, but they can be hard to find locally. Cool whites will probably work just as well, and are available everywhere.

Thanks Penfold. I'm thinking of building a 4' long 7" wide wood grow box. I will put 3 of those on a 4' x 2' self & have the light above. Do you think I could get away with growing the full crop of lettuce, kale & spinach under 4 6500K bulbs (attached to 2 shop lights)? Would that provide enough light for them?

T8's should really be placed quite close to the plants, or the light level drops off quickly. I would probably use one fixture for each grow box so that you have light directly over each plant. You could also hang reflective mylar along the sides for a slight boost.

You could always try 2 fixtures and add another later if necessary, but I think a third fixture will help a lot.