Once your perennials are established it will seem very easy just to sit back and admire your work, but you will have no time for that. Perennials do not last for ever, and the definition of the term is one that lasts for more than two years. As some die away you will have to remove and replace them with fresh plants. You can even move them about the garden since perennials are ideal for replanting. In fact many gardeners have a space set aside for starting off new garden perennials in a variety of colors that they can use later for filling in gaps as plants die. This avoids them having to wait until the plants mature.