Karen, how tall does the dwarf Crepe Myrtle grow? I just discovered a mosaic virus in my big hardy Hib. No cure. It will eventually kill it.
Soooo ... it's back to the drawing board because there is no sense in planting the additional Hibs like I had planned to do next Spring.
Now I'm thinking more Rose of Sharon and more Crepe Myrtles and Persicaria polymorpha. Other flowering shrubs and trees too.
This is my neighbor's yard across the street ... three of her Crepes are still blooming. The various Crepe Myrtles do have a difference in their bloom times.
I'm with Neal ... I'd definitely try them in zone 5.
