Ageratum October 1, 2017

This is Wayside Ageratum which is referred to as a perennial ageratum.  I don't find this to be perennial, as soon as the flower heads turn to seed the plants dries up.  I pull it all up, shake the seeds onto the ground and throw the dead plants away.  Next summer zillions of little plants pop up.  They stay very small through the summer and then in September they make a huge growth spurt and then bloom.