I planted some perennial Sweet Peas about 5 years ago....they are doing very well...I have heard that thay can become a pest...spreading ....growing everywhere with underground runners...just as the Obiedint Plant seems to do...I learned that here too....anyway I haven't had a problem with it....but I have heard people say that the sweet peas can take over and strangle your whole flower bed if it can....I do find alot of new plants growing here and there...I just pull them up...I do have horrible soil...total clay and rock....Michele >^,,^