Hardy perennial hibiscus (also called rose mallow) are showstoppers in my late-summer garden. Huge plate-size flowers in shades of pink, red or white burst forth from stout plants in late July/early August. Although the individual flowers only last a day, the succession of flowers can last for up to eight weeks. These amazing blooms have prompted many strangers to knock on my door to inquire about the bush with flowers the size of dinner plates. These Hibiscus flowers are amazing …