Though invented by Lovecraft in 1928 [needs confirmation], the name Cthulhu is probably derived from the Classic Greek word chthonic meaning subterranean, as apparently suggested by Lovecraft himself at the end of his 1923 tale The Rats in the Walls.
They're listed as a zone 5-9 plant but as a member of the hibiscus family, Rose of Sharon naturally prefers a warm climate. As a living fence, which is what you really want, you'll be much better off with some kind of evergreen. Juniper, spruce, pine, fir, there are many sizes and varieties to choose from.
Winter hardy to USDA Zones 8-10. This rose will not survive winters in St. Louis. Where winter hardy, it is best grown in medium moisture, slightly acidic, well-drained garden loams in full sun. Tolerates some light shade, but best flowering and disease resistance generally occur in full sun. Water deeply and regularly (mornings are best).