Unlike annuals, perennials grow year after year in the same location. Often called herbaceous plants, perennials produce fleshy stems that die down each winter, but their roots stay alive and send up new growth the following spring. However, in some areas of the country, perennials can remain evergreen all year around, while others can withstand winters. The greatest asset in having perennials within an outdoors space, is the ability to divide and transplant, providing the gardener with additional plants for the landscape.

Perennial Care
As with all plants, the key to growing successful perennials is choosing the right location, hardiness zone, and soil. Before planting, prepare soil by working in amendments like compost or well-rotted manure to ensure success. Work out your planting layout by using the height and spread information on plant tags to decide how far apart to plant. Perennials are best planted in cooler weather. To properly plant a perennial (1) dig a hole

that's wider but not deeper than the container. Remove plant from container and loose bottom of the rootball to stimulate root growth;(2) Dig a hole that's wider but not deeper than the container. Never shoehorn a plant into a hole that's too small;(3)Set the plant into the hole and cover roots with loose soil;(4) water lightly and add remaining soil; (5)firmly pack and water thoroughly; and (6) keep new perennials moist for a couple of months, allowing the perennial to establish itself in its new location.

Dividing Perennials
Perennials will eventually get too large for the space they're growing in and have to be divided. To divide plants (1) divide in either spring or fall,when it is not flowering allowing all the plant’s energy can go to root and leaf growth.Never divide perennials on hot, sunny days. Wait until a cloudy day, ideally with several days of light rain in the forecast; (2)depending on the type of perennial, dig up a clump using aspade,shovel,knife or hand. The more roots the better. Shake or hose off loose soil and remove dead leaves and stems. Perennials have several different types of root systems. Each of these needs to be treated a bit differently; (3)Replant immediately and water thoroughly. Some plants resent being divided and it should be avoided if possible. These include butterfly weed (Asclepias), euphorbias, oriental poppies, baby’s breath (Gypsophila), gas plant (Dictamnus albus), Japanese anemones, false indigo (Baptisia) and columbines (Aquilegia). Lenten and Christmas roses (Helleborus) are very difficult to move when more than a few years old. Lavender cotton (Santolina chamaecyparrus) and several other perennials are actually small woody shrubs and should not be divided. These include perennial candytuft (Iberis sempervirens), lavender, rosemary, southernwood (Artemesia abrotanum), and several other artemesias. These plants often have rooted layers (branches that have developed roots while touching the soil). The layers can be cut off the parent plant, dug up and replanted as though they were divisions.