To the best of knowledge there is only one orange asclepias tuberosa. Hello Yellow is yellow, obviously, and there is a red form available though I do not commonly see it offered by itself. More often I see a mixture called Gay Butterflies which has all three colors of orange, yellow and red.
As far as spreading, my original plant was purchased in a 4" pot and is 3-4 feet wide by 3-4 feet tall after 3 years.
