Perennials' inherent beauty is that they do not need to be re-planted each year because they live on a cycle. They have a callous root system and either die back or go dormant during certain times of the year. They come back year after year fuller and fuller. While some may love this fuller look, unfortunately, overcrowding leads to poor growth patterns as there is less space for the flowers and plants to grow adequately. That’s why splitting your perennials is recommended.