Definition: Perennials are considered to be ornamental plants that do not die after one season of growth. This does not mean they live forever. In fact many perennials are considered to be short-lived, lasting only 2-3 years. Rose campion is a short lived perennial, but because it self-seeds so readily, it appears to live much longer.
Not all plants with the ability to be perennial are hardy in all areas. This is why planting zones are so important. Knowing what zone you garden in will allow you to determine what plants will survive in your area.
The term perennial is generally reserved for plants with showy flowers, excluding ornamental grasses and other plants mainly grown for their foliage. The term herbaceous perennial further narrows the group to plants with soft, green stems that die back to the ground in colder climates. Trees, shrubs and other woody stemmed plants are excluded.
Examples:
Many of the perennial plants I admire are not hardy in my Zone 4 garden.
