How many of these would I need?

Say I was growing 3-4 plants under these lights how many would I need?

http://www.lowes.com/lowes/lkn?action=productDetail&productId=11629-3-64713&lpage=none

1 fer veg, dont use it fer flower. I didnt check the spectrum, hold. ..

Cudnt find the specs, but I'd say I'm right w/my last post

mh for veg, hps for flowering. You'll need a ballast and a socket as well you know, you can't just screw it in.