Landscape Plant Selection Requires Careful Consideration

The fall planting season will soon be upon us. And, if you'll be adding plants to your landscape, give some careful consideration to your new plant selections.

Not all plants do well on all sites. Take time to analyze your landscape and your needs. Choosing the right plant for the right location is the key to success.

If your gardening time is limited, choose sturdy native or desert adapted plants. Palo Verde, mesquite, desert willow and other desert species are relatively trouble-free. Yes, they still must be cared for initially, but once established they require only minimal care. On the other hand, introduced species like oleander, bougainvillea, and bottle trees require regular watering, pruning, fertilizing and pest control. It's all a matter of how much time you wish to devote to working on maintaining your landscape.

Whether you choose native or non-native plants, avoid selecting those that are susceptible to Texas Root Rot. This disease is truly the worst in the desert, causing plants to die suddenly, and seemingly without cause. A fungus disease, Texas root rot lives in the soil and infects the roots of susceptible plants, killing them. If the root rot organism is living in your soil, there is virtually nothing you can do to get rid of it. You can, however, grow native and desert adapted plants. They are resistant to the disease and are rarely bothered. Surprisingly, some non-natives such as; palms, eucalyptus, citrus, oleander, and crepe myrtle are also resistant. Plants that are most susceptible to root rot include; bottle tree, cottonwood, pepper tree, elm, fig, and stone fruits.

Make sure the plants you select are cold hardy for where you live. In a broad sense, temperature zones in Arizona are based on elevation. The higher the elevation the colder. Here in Tucson higher elevations usually mean warmer winter temperatures. This is because cold air drains down from the higher to the lower elevations, collecting along washes and rivers. Night-time temperatures in these low spots can be as much as 10 to 15 degrees colder in the winter than higher locations. If you live in a cold spot, avoid planting frost prone plants like, hibiscus, sago palm, bougainvillea, and citrus. Yes, you can baby them through the cold by covering them, but it's a lot of work and not always successful.

All plants require some amount of sunlight, but some species need many hours of full sun while others do best largely in shade. Before choosing plants for your landscape, observe how many hours of sun and shade various parts receive. Remember to take into account that the angle of the sun changes with the time of year. You will probably have more hours of direct sun in summer than in other seasons.

Plants requiring full sun need at least 6 hours daily and do best if they receive sun all day long. Large trees do best in full sun, while some small trees do better in sites that are shaded part of the day.

Plants that can tolerate partial shade will need 3 to 4 hours of direct sun. Shade loving plants will adapt to sites with less than 2 hours of direct sun or with filtered sun. Some shade loving plants can tolerate direct exposure to morning sun but may suffer if directly exposed to 2 or more hours of mid-day or afternoon sun.

Finally, before purchasing your landscape plants, determine whether there is enough room for them to grow. This is especially important when selecting trees. Little 5 gallon mesquites grow up to be big and tall 20 footers with equal spread in no time at all. Make sure you leave enough room between plants and the house, walks and driveways. Set plants no closer than one-half their mature spread from these and other obstructions.

Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona, 520-626-5161.
Material originally appeared in Arizona Daily Star gardening column, on August 16, 1998
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