Shrub Althea is known by several common names: Rose of Sharon , Rose Althea, and St. Joseph's Rod. The Scientific name is Hybiscus syriacus, and the flowers show their hybiscus heritage in the structure of the flower. (They look like okra, don't they, and cotton.) My mother and grandmother called them simply Althea, and that is the name I use most often. The lavender usually starts blooming in late July or early August. The double pink follows a few days behind the lavender. This year they were a few weeks later blooming, I suppose because of the drought. I never water them, they have to make it on their own, and they are very capable of tending to themselves. I had read online that the lavender was particularly prone to reseeding but had never seen it in my own yard til about 3 years ago. Now I have two new shrubs that have come up nearby the mother shrub. I do not consider them to reseed at the nuisance level though and new plants can easily be controlled.
Altheas can be pruned if they become too large and this is best done in spring as it flowers on new wood, and pruning early won't cut back on the flowers either.
Also, an Althea bush makes an ideal place for a cardinal nest. I have had one several years in mine. They build a nest about 3 /4 feet off the ground.