One ballast running two lights

Somewhere I read that one ballast could be switched to run two lamps. One lamp would be off for 12 hour while the other lamp was on. After 12 hours the lamp that was off would switch on and the lamp that was on would be switched off. I was thinking that this would be a great way to avoid winter heating expenses in the flower room. I would install a light proof barrier between the two hoods and run off one ballast. The problem is that I can't figure how to make it work. How do I get the power cords running from the two lamps to fit into the single outlet provided on the ballast? I know I could simply buy another ballast, but if I can avoid the expense it has got to be worth a try.

you need a relay, a small electronic component; runs about 20-40$....

ive ghetto rigged one of these things, i just cut off the cord coming from my ballast going to the bulb/reflector, and i hard wired a surge protector to it. then i took my two reflectors, both being HPS because thats what the ballast was for. and pluged them into digital timers and then into the surge protector, but it was important to set the timers with some space between to allow the ballast to cool for a few minutes, i left a 5 minute gap between when one turned off and the other started its 12 hour cycle.

Thanks Kindprincess. I was asking at our local hydro shop and they had not heard of such a thing. I take it the two power cords going to the lamps plug into this relay as too would the power cord coming from the ballast. Any idea on where to purchase one?

Thanks to you too BoostJunkie. I may experiment with this.

google 120v 15a flip flop relay

wire according to schematics. if you get one and can't figure it out, pm me. i'll help