I bought this in Florida as a bedding plant (it just jumped into the cart!), brought it back to Washington, stuck it in a mixed container on the front deck and it has been flowering ever since. It's been planted about 5 months and before I cut it back this morning it was about the size of a basketball with ?100 flowers.
I love kneeling down and examining the flowers but it's one of those plants that is never as good in the garden as it is in the shopping cart. There are so many perennials and annuals with beautiful, multicolored, complicated flowers that don't do much bedded out. Containers work for me. For one thing, they legitimize planting single plants, a practice that produces a spotty garden I admit guiltily. As a bonus, large containers bring the flowers closer to eye level.
Cuphea is a medium sized genus of new world plants mostly tropical or at least southern, with a few ranging up into Zone 6 or even beyond. Because of the oil content of their seeds (note the common name waxweed) some Cupheas are being investigated as potential fuel sources. One of my favorite plants in the Florida garden and one of the only ones we kept from the inherited landscaping is Cuphea micropetala. It's evergreen in Wildwood and is usually flowering for the winter holiday season. On my list of things I have been meaning to do but haven't is: bring a piece up here and try it as a dieback perennial. I bet it would live at the base of the east-facing wall. Someday.