I doubt they're really 150 watt CFLs, not from Home Depot. They're most likely 42 watt CFLs or something, that are '150 equivalent watts' - e.g., intended to replace a 150 watt incandescent bulb for household lighting. I don't know anyone who'd buy three 150 watt real CFLs, because they could get a 600 watt HPS with a digital ballast for about the same money.

My 125-watt CFLs (one for each of two veg cabinets) were about $100 each (including reflector), and the 150s were significantly more expensive than that.

The recommended wattage per square foot is 50ish. You have 6 square feet so you should aim for 300 watts. Assuming you have 3 42-watt bulbs, you have about half the lighting you need for that area. Add a few more bulbs, and keep them as close to the plants as you can without burning them, and you should be fine. You could probably grow them all the way through with just the three bulbs, but if you add more lighting you will be richly rewarded by your green ladies later.