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Extension > Garden > SULIS > Maintenance > Sustainable Herbaceous Plant Maintenance > Cultivated Perennials

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Cultivated Perennials

Perennials Herbaceous perennials live and bloom for two or more seasons growing seasons; they dieback each fall and reemerge the following spring. Some perennials may live a few seasons while others may live indefinitely with the proper care and environment.

Perennials are considered by many to be the king of herbaceous plants because of their longevity and their immense variety of foliage, flowers and form. The range of perennials available is vast, and includes some herbs, vines, ground covers, ferns, landscape grasses, and other type of plants. This section covers cultivated perennials; that is, perennials that require various levels of maintenance such as deadheading, cutting back old growth to encourage new, pruning to improve air circulation, occasional division of plants, etc. Gardeners who are diligent are rewarded with spectacular color and texture. According to Mike Heger and John Whitman in Growing Perennials in Cold Climates, gardening with perennials is like "painting with a full palette of colors".

To successfully grow perennials, it is important to select plants that are suited to the climate and the landscape. Like trees and shrubs, perennials are incorporated into a landscape with the idea that they will be there for years to come, so hardiness is an important characteristic to note. Some perennials are winter hardy and can survive our cold climate while others require winter protection from the elements. These perennials are considered to be "tender perennials".

The amount of sunlight a perennial needs is an important factor in plant and site selection as it usually affects moisture levels as well. Most perennials prefer full sun and moist, well-drained soil. Others, such as black-eyed Susan (Rudbeckia hirta) and certain daylilies (Hemerocallis species and hybrids), flourish in sunny, dry conditions. For shade-loving perennials, see Planting under Existing Trees in this website, and Perennials for the Shade.

Because perennials are long-lived plants, gardeners should be aware of the mature size and therefore the spacing requirement of perennials. Some taller perennials such as garden phlox (Phlox paniculata), or climbing perennials may also need the support of a trellis, fence or stakes if they are planted in a potentially windy area. Tall perennials may also shade small perennials and may also block airflow and rain from reaching these diminutive plants. Mature plant sizes of many perennials and other herbaceous plants can be found by using the Plant Selection Database located on this website. A good reference book is Growing Perennials in Cold Climates written by landscape professionals Mike Heger and John Whitman.

Finally, the fun part - color, flowers, foliage and texture. Because of their longevity, extra time should be taken to mix and match perennials with complimentary colors, textures and alternate bloom times to provide continual color and beauty throughout the growing season.

For a website dedicated exclusively to perennials, visit Perry's Perennial Page. It has a perennial plant database that includes images and facts about each plant as well as links to other sites about perennials and perennial-related publications and organizations.

For more on proper plant selection based on site and plant characteristics, see Plant Elements of Design plant selection database.

Click on any of the following headings and link to chapters that explain care and maintenance of herbaceous plants.

Dividing Perennials
Dividing Plants
Dividing Rhizomes
Starting Plants from Seed
Collecting and Saving Seed
Self-Sowing Plants
Propagation by Vegetative Cuttings
Layering
Propagation by Spores
Transplanting Seedlings, Cuttings and Divided Plants
References

Staking, Supporting and Training Plants
Methods of Supporting Plants
Materials & Structures
Training to Improve Plant Health (FUTURE)
Training Plants for Ornamental Purposes (FUTURE)
References

Pruning
Cutting Back Plants
Pruning for Plant Form
Pruning to Prevent Disease (FUTURE)
Deadheading and Pinching Back (FUTURE)

Mulching & Watering
Why Use Mulch?
Application of Mulch
Mulching for Weed Control
Mulching for Winter Protection
Mulching for Moisture Control
Organic Mulches
Synthetic Mulches
Watering Your Landscape
How to Determine the Frequency and Rate of Watering
Water Quality and its Effect on Plants
References

Nutrition, Fertilizers, and Compost
The Basics of Plant Nutrition and Fertilizers
Soils (FUTURE)
Compost (FUTURE)
Fertilizer: the Do's and Don'ts
Organic Fertilizers (FUTURE)
Inorganic Fertilizers (FUTURE)
Salt Tolerant Plants

Weed Management
Weed Identification and Lifecycles
Cultural Management Methods for Weed Control
Pruning for Weed Control (FUTURE)
Herbicides
Understanding Labels (FUTURE)
Alternatives to Chemical Herbicides (FUTURE)
References

Diseases and Insects
Diseases
Insects
Integrated Pest Management (FUTURE)
References


References:

DiSabato-Aust, Tracy, The Well-Tended Perennial Garden. Timberland Press, Portland, Oregon. 1998

Heger, Mike and Whitman, John, Growing Perennials in Cold Climates, Contemporary Books, Chicago, Illinois. 1998.

Iowa State University, "Staking Perennials", Horticulture and Home Pest News, Sherry Rindels, May 19, 1995. Updated by John VanDyk, December 26, 1997. http://www.ipm.iastate.edu/ipm/hortnews/1995/5-19-1995/stake.html.

Ohio State University Extension, "Herbaceous Ornamentals: Perennials", Master Gardener manual, Jack Kerrigan and Margaret Nagel.

Ohio State University Extension, "Methods of Staking Perennials", Master Gardener online publication.

Snyder, Leon C., Native Plants for Northern Gardens, Andersen Horticultural Library, University of Minnesota, St. Paul, MN. 1991.

University of Minnesota Extension, "Dividing Perennials", H140P, Susan H. Barrott. August 1999. http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/h140perennialdivide.html

University of Minnesota Extension, "Perennials for the Shade", INFO-U publication #428, Mary S. Joyce and Deborah L. Brown. 1997. http://www.extension.umn.edu/garden/master-gardener/volunteers/teaching-tools/perennials-for-the-shade.ppt

University of Vermont Extension, "To Stake or Not to Stake", The Greene Mountain Gardener Summer news article, Dr. Leonard Perry.

University of Vermont Extension, "Perry's Perennial Pages: Photos and Files" , Dr. Leonard Perry. http://www.uvm.edu/~pass/perry/

University of Virginia Cooperative Extension, Virginia Tech and Virginia State Universities, "Sowing Perennial Seeds", Diane Relf. April 1997. Originally published by Robert E. Lyons, Professor of Horticulture, in The Virginia Gardener Newsletter, Volume 7, Number 8.

Yockey, Terry L., "A New Lease on Life: Dividing Perennials". Northern Gardener, April 2002, vol. 130, no. 4. Minnesota State Horticultural Society. St. Paul, MN.

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