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Shrubs for Northern Arizona Above 6,000 Foot Elevations
Cooperative Extension, College of Agriculture & Life Sciences, The University of Arizona

Written by
Tom DeGomez, Associate Agent, Agriculture and Natural Resources


Shrubs can greatly enhance the landscaping of your home year round. Shrubs offer many features
that trees or perennial herbaceous plants cannot. They are small enough to be planted in many places that trees do not fit yet are large enough to fill large spaces and provide mass and structure. They contribute a variety of ornamental qualities to the landscape such as beautiful flowers, striking foliage, attractive fruits or even colorful stems. Their longevity adds life to the landscape during the
dormant season and for years to come.

Above 6,000 feet, suitable landscape plants are quite different from those for low elevation desert. High elevation winters include snow and temperatures below zero. Winter hardiness is one important factor to consider when choosing a shrub. Many may think that because this part of Arizona is no colder than states to the north that plants will perform similarly or better. However, low levels of precipitation in May and June, combined with strong drying winds and late spring or
early autumn frosts make it difficult to grow plants which are otherwise low temperature hardy. In addition, large fluctuations in temperature in the winter months may have an adverse affect on some otherwise hardy shrubs.

Microclimate has a strong influence on the kinds of plants that will succeed on a given site. A tree or shrub that does not grow well in an open, windswept location or cold meadow bottom at 5,000 feet may be quite satisfactory at 6,000 feet in a protected location or against a warm south facing
slope, where it is said to be in a milder microclimate. A key to successful landscaping in Northern Arizona is an understanding of location of the planting site and careful selection of plants that will thrive under those climatic conditions.

Types of shrubs

There are two basic types of broad-leaved shrubs for high elevation landscapes. The first group consists of deciduous shrubs, or those plants that drop their leaves during the winter dormant season. Most are hardy, undemanding plants with attractive flowers, form, or fruit. The second shrub type are broad leaved evergreens, which keep their green foliage year round. Many require a sheltered location and extra attention to soil preparation and irrigation. Broadleaved evergreens provide bold foliage as well as striking flower or fruit effect. Only a few species of broadleaved evergreens grow well in Northern Arizona.

Conifers are another type of shrub that is widely planted at high elevations. Included in this
group are the junipers, and dwarf pines and spruces. These plants offer a year round display of color and texture but do not have showy flowers. They do provide mass and structure to the landscape and can be used in conjunction with many flowering plants as a backdrop or foundation.

Ways to use shrubs

Shrubs can be enjoyed for the beauty of their flowers, fruit, foliage, or form, but they should not be thought of simply as decorative greenery for the exterior of the home. They have many practical uses to make your landscape more pleasant and functional.

The most common way that shrubs are used in the American landscape is in the foundation planting around the house. While this practice originated during Victorian times to cover the foundation of large Victorian style house, the practice continues today though there is less of a need for it. Foundation plantings none-the-less can enhance the style of a house, soften its look, tie it to the surrounding landscape and direct attention to the primary focal point of most houses, front door.

Shrubs can also be used to define spaces around the house. Shrub borders can attractively delineate the boundaries of your property and turn a yard into a garden by creating privacy and limiting views. Grouping shrubs together to create vertical planes or walls can enclose an area to create outdoor rooms. These walls can be evergreen, deciduous, or both. These borders can also serve as the backdrop for annual and perennial flowers.

Other important uses of shrubs are to indicate the direction you want people or cars to travel, to screen unwanted sights, to buffer noise and to create privacy. Shrubs can be planted to effectively block wind and to control erosion on some slopes.

Shrubs that are particularly beautiful and with long term interest can make fine specimen plants to be placed so that they stand out in the garden and can be viewed from all sides and from indoors.

Last, but not least, hardy shrubs can modify climate by trapping the warmth of the sun and deflecting strong drying winds and drifting snow. The microclimates that result extend the season for using and enjoying outdoor areas.

Selection of the right shrub

Shrubs are often selected simply on the basis of the color or size of their flowers. However, your first concerns should be its cultural requirements and the mature size and shape of a plant. Also important are the foliage qualities and branching structure of the shrub for long-term appeal. Many flowers last less than a month.

The key to successful gardening is to understand the conditions that your property has to offer and then to invest in plants that are suited to your site. Light, soil, air, temperature, space, and precipitation are all factors that can vary the climate around your home and should be considered when making your selections. Changing light conditions around your home is limited to adding trees for shade or removing trees for more sun. Soils can be amended with organic matter to provide better growing conditions. Organic matter can loosen a clay soil and increase the ability to hold moisture for a sandy soil. The amount of moisture available is one of the few conditions that you can easily modify but this can be expensive for larger plantings.

Many gardeners find that their property has many different microclimates and can therefore expand the range of plants that can be grown. Plants that are on the borderline of hardiness may fail if planted out in the open but could thrive in a sheltered location. A southern exposure may be too harsh for some plants but the additional warmth may be a bonus for others.

Large shrubs often look best with a tall house while smaller shrubs compliment smaller structures. Remember that shrubs will mature and that small attractive shrub that you selected at the nursery may eventually outgrow its space. A good rule of thumb is to choose plants grown near doorways that obtain a mature height of about one-third the height of the eave. The mature height of corner plants can reach two-thirds the height of the eave.

Allow enough space for your shrubs to grow in both height and width. Proper spacing will spare yourself endless pruning or the expense of ripping out overgrown plants and replacing them after several years growth. Consider using a dwarf cultivar of a desired shrub if your space is limited.

Once you have mastered the growing conditions and size requirements of your site, now comes the pleasure of selecting plants for the effect you want. Ask yourself what do you want the shrub to do in the landscape? Do you want to create privacy or block wind? Are you most concerned with blending your house to the landscape? Do you want to grow shrubs with fruit that will attract birds? Are you interested in a seasonal garden that allows flowers to create a display for short periods of time? Give consideration to foliage quality, seasonal changes, fruiting habit, branching pattern and other unique features that each plant has to offer.

The following table lists some of the most useful shrubs for Northern Arizona above 6,000 feet in elevation as well as their landscape uses and cultural requirements.

Acknowledgement

Special thanks to Hattie Braun, Master Gardener for her assistance on this publication.

 

Tables: Dendroctonus and Ips Species that Attack Pines in Arizona
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Document located http://cals.arizona.edu/pubs/natresources/az1285/
Published January 2003
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