Designing and Planting Perennial Borders - August 30, 2000
Jeff Schalau, County Director, Agent, Agriculture & Natural Resources
Arizona Cooperative Extension, Yavapai County
Perennial borders are "flower beds" dominated by herbaceous flowering plants. Well-designed perennials borders are easy to maintain once planted and provide color and texture year-round. Most of the work and expense comes during preparation and planting. During the first year, weed control will be necessary and should be a high priority. In subsequent years, light fertilization, mulching, and the addition of a few annuals will cost little and enjoyment will be great.
Site selection is important. Most effective perennial borders have evergreen shrubs, a solid fence (not chain link), or a building for a background. Scale is important here: large borders need larger backgrounds that smaller ones. The soil must also be weed-free (see last week's column if Bermudagrass is present). In areas with annual weeds, pre-emergent herbicides can be used, but hand pulling and mulching will usually suffice. Organic matter and ammonium phosphate should also be incorporated into the soil where perennials will be planted.
Shape of the bed is also important. At this stage, I recommend getting out the graph paper and drawing the bed to scale. Avoid straight edges and use bold sweeping curves. The border is easier to maintain and more visually pleasing if edged with bricks or rocks set flush with the ground level. After defining the space, visualize the height and shape of plants when they mature. For example, hollyhocks can grow to five feet high or more. You probably don't want a row of hollyhocks in front of a low growing background shrub. They would look best against a taller background.
The foreground is filled with a variety of interesting colors and textures. Leaves as well as flowers create interest. A few medium-sized shrubs and tall perennials can also be planted in the middle of the bed to create interesting patterns. Again, keep mature plant height in mind. Smaller plants should be organized into drifts and clumps. Drifts are elongated groupings that flow through the border. Clumps are circular groupings of plants or can be one large plant. The drifts and clumps should also vary in size and be proportional to the space.
Proportionality can be developed in terms of masses of color and texture. Five to seven identical small plants grouped together will always look better than a random collection of small- or medium-sized plants. Flower colors should not clash. Yellows, oranges, and reds look good planted in adjacent clumps and drifts. Blues and purples also compliment each other. Conversely, a hodge-podge of colors will often look disorganized and unappealing. Annuals can also increase your color palate and don't forget that grasses can also be used.
Here are some additional rules-of-thumb for perennial borders. As mentioned before, tall plants in back, medium height plants in the middle, and short plants in front. If bordered by a lawn, leave enough space to allow room for mowing. Plant height is best limited to 2/3 the width of the border, e.g., no plants taller than four feet in a six foot wide border. The most logical way to choose a plant is first by location, second by period of bloom, then by height, and finally, by color. Don't crowd plants too close. A little bit of bare ground helps define space and adds interest to the planting.
The overall objective in designing a perennial border is to have a harmonious grouping of interesting plants that change, yet remain balanced from season to season. Aim for a continuous succession of color. Take photos of the border at different times of year to monitor its progress and identify potential improvements. Don't be shy about your border design. Just have fun with it! If needed, plants can be moved around, added, or deleted from the border to improve it over time.
The University of Arizona Cooperative Extension has publications and information on horticulture, natural resources, animal science, family consumer science, and 4-H youth development. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at firstname.lastname@example.org and be sure to include your address and phone number. The Yavapai County Cooperative Extension web site is http://ag.arizona.edu/yavapai/.
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Last Updated: March 15, 2001
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