As I recall that one gets 4ft. high and wide, sort of a shrubby variety. I'd decide how big a pot you can handle, and go straight to that so it will make a big lusty root system.
Then if it's struggling in the mid-summer heat and you're having to water it twice a day to keep it from wilting, you'll need to give it a haircut or two - prune it down to size. That will probably keep it blooming nicely through the fall for you. It may be a xeriscape plant and very drought tolerant but in a pot it's going to still need regular watering. Don't let it dry up so the soil in the pot becomes a solid brick or the plant will die. You might want to put it in a group of pots or somewhere the pot is not exposed to the direct sun (it will bake).
