Purple perennials are a favorite with gardeners because they come in a variety of shades and mix well with other flowers. Purple flowers combine with white, pink, yellow or even orange flowers to create attractive flower beds. When choosing perennials, consider the growing needs of the plants and the conditions in your garden. Choose plants with complementary foliage and textures, and don't mix too many different plants in one location.
Inspect the foliage and flowers of the perennial and note any unique characteristics. Easily recognized allium is a member of the onion family and has one large ball comprised of many tiny blossoms on the end of a long, slender stem. Vinca is a spreading groundcover with dark, glossy leaves and small purple flowers. It quickly covers an entire flower bed, and is grown mostly for its foliage. Another popular groundcover, lamium, has light green, variegated leaves and purple, pink or white flowers. Bellflowers look like tiny bells.
Consider when the plant blooms. Crocus bloom in early spring and resemble small tulips. Iris also bloom only in the spring and form guazy, multi-petaled blossoms on a tall stem.
Inspect the growth pattern. Several purple midwest perennials produce spikes of flowers, including delphinium, salvia and sage. Delphinium grows to a height of 4 feet, and produces delicate flowers. Salvia grows to 14 inches tall, and produces small, bright purple stalks of flowers. Sage has a shrub-like appearance. If the plant vines, it is probably clematis. Purple coneflowers resemble sunflowers.
Smell the flower. Lilacs and lavender both have distinct fragrances that identify them.