15 Fresh Seeds w/Instructions This tropical-looking beauty will make you forget that blue is perhaps the hardest color to find in nature. Rose of Sharon grows as a small tree or shrub, and the large blooms of Blue appear continually from late summer until frost. A stronger grower than 'Blue Bird', it performs well in full sun and hot weather. Adaptable to many soils, but best mulched in the winter in colder zones. The plants produce big bright flowers that appear endlessly starting in high summer.