Tree Care Corner
by Tracey Till, Class of 2016 Plant Sciences (B.S.)
It’s almost tree planting season here in southern Arizona. Planting a tree is one of the easiest, most affordable and satisfying ways to make a positive impact on the environment. Why plant a tree? They improve our quality of life, reducing summer temperatures, absorbing carbon dioxide, suppling oxygen, reducing storm water run-off, and soil erosion, protect water quality, and beautify our surroundings. When strategically planted they increase property values and reduce energy use and utility costs. Of course, trees generate more of these benefits as they mature, so they must be well selected, planted and managed to ensure longevity.
Young trees adapt readily to transplanting. Trees acquired from community organizations, like Trees for Tucson, or from a local nursery are most likely to be adapted to our region. When choosing a young tree, make sure to inspect the root ball by carefully removing it from the container. Roots should reach the edge of the root ball, be whitish in color, but not circle the inside of the container or grow through the drain holes. Circling roots are a sign of poor nursery practices leading to a tree that is pot-bound. Poor quality nursery stock like this should not be purchased. Circling roots eventually contrict water moving into the tree, causing girdling that limits growth and eventually kills the tree. If only a few roots are circling, cleanly cut them away with a sharp tool. Roots can also be manually splayed so that they will grow out into the native soil after transplanting to provide stability and securely anchor the tree.
Planting a tree can seem deceptively simple. Anyone can do it. However, problems from improper planting don’t always show up till years later. Get off to the right start by following this easy guide to planting a tree.
Tree Planting Steps:
- Water the area the planting area a few days before digging.
- Dig the planting hole at least twice as wide as the root ball, but no deeper than the height of the root ball. Planting so that the top of the root ball sits slightly above grade, or "planting proud" corrects problems that may be encountered if the base settles and prevents the tree from sinking or burying the trunk.
- Carefully slide the root ball out of the container, holding by the root ball and never the trunk. Check for root matting or circling. If needed, cleanly score the sides and bottom of the root ball to cut and separate roots. Only cleanly cut roots will regrow.
- Place the tree carefully into the planting hole. Remove just enough soil from the top of the root ball to expos the root collar, which should be level or slightly above the surrounding soil. Adjust the depth of the hole if necessary.
- Backfill with native soil. There is no need to add amendments. Do not compact backfill.
- Form a berm just outside the root ball to create an irrigation well. Water in well. Be sure the base of the trunk is not the lowest point in the grade to allow water to
- Apply a 2-4 inch layer of mulch to conserve water and cool the roots of the tree. Make sure to keep mulch away from the trunk, as this can cause moisture to collect and the bark to rot.
- Trees should be watered deeply and the entire root zone should be wetted. During the first year, the tree may need to be watered as often as once every 5-7 days. Once established, watering can be less frequent. Exact watering needs depend on the type of tree, type of soil, and the time of year. Remember that even drought tolerant trees need consistent watering to become established.
Special Considerations For Siting Trees
There are important guidelines to follow when selecting the place to plant a tree near your home. Trees should be planted at least 5-10 ft. from buildings. Some trees have been known to damage foundations, so before you plant near the house check whether it is notorious for this. Take into consideration the mature height and spread of the tree you are planting to decide the best location.
Special considerations should be made if you have power-lines near your property. Trees planted within 15 feet should not have a mature height of more than 20 feet. Trees planted 20 to 50 feet from a power-line should not grow more than 40 feet tall at maturity. Any trees that grow more than 40 feet tall should be planted more than 50 feet from the power-lines. This avoids the hazards of a tree branch falling on a power line, preventing damages and interruption of utility services. A few tree that are recommended for planting near power-lines are Foothill Palo Verde (Parkinsonia microphylla), Desert Sweet Acacia (Acacia smallii A. minuta), Mescal Bean (Sophora secudiflora), and Texas redbud (Cercis canadensis var. texensis).
For energy conservation in the home, plant trees that will provide shade to west and east windows. Trees can also be planted to shade air conditioners, patios, and driveways. Using deciduous trees on the south side of buildings allows winter sunlight to filter through. Evergreen trees that keep their leaves year-round are great for windbreaks, protecting your home from heat loss in the winter and keeping your air conditioner efficient in the summer.
Arizona climate varies widely from city to city and microclimates vary across a property. Variations in temperature, soil type, elevation and precipitation all affect which trees you should select for planting. Native trees are always a great choice because they have adapted over millions of years to the local environmental conditions. However, other arid-adapted non-native plants are often best suited for many urban microclimates. To learn more about the conditions in your area and the recommended trees, see the resources linked here. org/How-to-Plant-and-Care-for-Trees
Resources Referenced:
How to Plant and Care for Trees (Arizona Community Tree Council)
Trees Are Good (International Society of Arboriculture)
Planting Guidelines For Trees (UA Cooperative Extension Bulletin AZ1022)