Unlike annual plants, which must be replanted each spring, herbaceous perennials die to the ground at the end of the season, and then regrow from the same roots the following year. People grow perennial flowers because they are such easy-care, dependable performers. Some species, such as lupines and delphinium, are so called "short-lived" perennials, with a lifespan of just three or four years. Others may live as long as fifteen years, or even, in the case of peonies, a lifetime. Bloom time may last for only two weeks each year, or may extend over two or three months.Most perennials, thrive in well drained soil, Some perennials contain themselves in a nice, neat mound, while others will take over your entire garden. Some species should be cut back in midsummer, while others may die if you remove their foliage