Slightly variable in colour, you can see that the seed family that these particular plants came from is not quite as purple as their common name suggests. They are giant though, and nectar feeders love them no matter what their colour.
They grew to roughly 5’ tall in a dry meadow setting. In a garden setting I suspect that they would exceed this by a foot or even two. They are nice and sturdy, holding up well to a windy summer, despite limited support from neighbouring plants.
Pollinators of all types, bees large and small, butterflies and hummingbirds, all visited the blooms regularly for the nearly two months that they were offering nectar, from mid July to early September.
These plants were photographed in their second year from seed and have a base width of maybe 18”. I doubt that they will get all that much wider and they don’t have a tendency to wander.
These are growing in full sun and seemed to be very happy with that. I suspect that they would also be alright in light shade, as long as they received either a full morning, or a full afternoon of sunshine. Making all that nectar takes energy!
Seeds collected from plants grown from seed purchased from Beaux Abres