Perennials are the backbone of the flower garden. Unlike annuals, which need to be replaced each year, perennials go dormant over the winter and emerge again in spring. Many perennials will live for decades, among them peonies, daylilies, and hostas. Others live for only a few seasons and must be replaced every few years. Because they need to store up energy to return and bloom again, most perennials have shorter blooming seasons than annuals. Typically, they flower for only three to four weeks, sometimes less and sometimes more, and offer foliage and perhaps seedpods as interest for the rest of the growing season. However, when many perennials are used together in the garden—such as in beds or borders—the progression of different plants in bloom from spring though summer to fall can provide a fascinating array of combinations of colors, textures, and habits.
FIRST A DISGUSTINGLY PERSONAL PROMOTION - MY LIFE PARTNER NANCY SZERLAG HAS A BOOK ON PERENNIALS FOR MICHIGAN. VIRTUALLY ALL THE INFORMATION WORKS FOR FOLKS LIVING EAST OF THE MISSISSIPPI RIVER AND NORTH OF TENNESSEE. IT IS A GREAT BOOK FOR THOSE OF YOU JUST DIPPING YOUR TOE INTO THE WORLD OF PERENNIALS
NANCY'S BOOK IS AVAILABLE FROM AMAZON.COM.
FREQUENTLY ASKED QUESTIONS ABOUT PERENNIALS
When do I cut back my perennials?
Spent flowers can be cut off as soon as flowering has finished, to prevent the plant from expending energy forming seed instead of growing more roots or stems. Cutting off spent flowers is called deadheading, and it also helps keep the garden looking neat and trim, and may encourage rebloom in some varieties. The plant itself should be allowed to grow until most of the stems and leaves have yellowed, usually after a hard frost in fall. Cut the plant down close to the ground; if there is a small mound of foliage at the base of the plant, allow that to remain.
Some years ago Liz Ball wrote the following article about how to decide if a perennial is really what they call a "better plant". This is an article more for gardeners than for yardeners but for anyone interested in perennials it is a wonderful article.
Perennials for All Reasons: Better Plants for Your Home Landscape.
by Liz Ball