- Author: Janet Hartin
Do you have Spring Fever? If you have adequate space, why not leave a legacy to your children's children by planting a tree? When the right species is planted in the right location and receives the right care, landscape trees can be enjoyed for 100 years or more.
Urban trees cool and shade urban heat islands, absorb and store carbon, produce oxygen, filter pollutants from air and water, reduce soil and water erosion, reduce internal energy needs and related costs, provide habitat, and beautify neighborhoods. Sadly, the average lifespan of our landscape trees is less than 20-25% of their potential due to poor selection and care.
Selection and Care Tips:
Plant in Spring or Fall. Avoid planting landscape trees during the heat of the summer. (Deciduous bare-root fruit trees, on the other hand, should be planted during the winter when they are dormant.)
Choose recommended species for your climate zone. Select trees based on your Sunset climate zone (zone 13 for Coachella Valley) because they are more precise than USDA zones and include information related to high temperature adaptation s as well as low temperatures which is the basis of the USDA zones).
Choose recommended species for your microclimate (shade/sun, soil conditions,water requirement, available space, etc.).Two reliable search engines that allow users to search by multiple criteria (size, water needs, flower color, ecosystem functions, pest susceptibility, etc.) are: Urban Forest Ecosystem Institute : https://selectree.calpoly.edu; California Native Plant Society: https://calscape.org/search.php. 'Lush and Efficient' is also a very useful publication produced by the Coachella Valley Desert Water Agency. Download it here: http://www.cvwd.org/DocumentCenter/View/813/2006-Lush--Efficient-Revised-Edition-PDF?bidId=as is Water Use Classification of Landscape Species IV: http://ucanr.edu/sites/WUCOLS
Four species that we have recently identified in our research on heat and drought resistant trees that are highly recommended for the Coachella Valley are:Netleaf Hackberry (Celtis reticulata), ‘Maverick' Mesquite (Prosopis glandulosa), Pistacia ‘Red Push' (a hybrid between P. atlántica × P. integerrima) and Desert Willow ‘Bubba' (Chilopsis linearis)
Avoid circled, girdled roots. Remember to inspect the root system of container trees. Avoid specimens with severely circled and girdled roots. Root pruning will not solve the problem and the resulting tree is much more prone to failure later. This occurs because the upper portion of the tree continues to grow and expand while the root system lacks the breadth and architectural strength to support the tree. Many times a tree will look fine for several years and - seemingly - very suddenly, topple in winds that otherwise it could sustain with a more adequate root system. Only when the tree falls does the owner actually notice firsthand that the root system is the same size it was when the tree was planted years before!
Check drainage before you plant. Dig a hole where you are planning on planting the tree, fill it with water, and make sure it completely drains within 24-hours. If it doesn't drain, don't plant a tree there. In some cases, trees are carefully selected based on species and location only to perish ten or more years later due to poor drainage and water-logged soil. Trees often die in these situations due to a lack of aeration setting them up for disease-causing fungal pathogens. tree planting hole drainage test tree planting hole drainage test Planting the tree.
Dig a planting hole at least 2-1/2 times the width of the container (in clay or compacted soils make the hole at least 4-5 times wider) up to two inches shallower than the depth of the tree in the container to compensate for settling. Use a shovel or trowel to roughen the soil on the sides of the hole to encourage root growth into the native soil. Remove the tree from the container along with any loose soil that covers the lower part of the trunk. Carefully place the tree in the planting hole, keeping the trunk flare (the area where the trunk widens and connects with the roots) 1-2 inches above the existing grade. Gently fill the hole with the same soil that was removed. Do not add soil amendments or compost, another common cause of circled and kinked roots. Water the tree regularly until established (one or more seasons).
Water immediately after planting making sure to moisten the entire root system and a few inches below it. Many recently planted trees die due to the common misconception that they require little or no water if they are native or low water using species! Recently transplanted trees have a small volume of roots that dry out very quickly. Water trees separately from turf and surrounding higher-water using plants.
Water newly planted trees regularly through the first season. Trees in sandy soils require more frequent watering than do trees in heavier soils with appreciable clay content. Heavier soils absorb water slower but retain it longer and should be watered longer but less often. (After trees are fully established, irrigation frequency should be reduced but more water should be added during each irrigation.) Avoid staking trees unless necessary.
Stake trees only if they were staked at the nursery and/or if they are planted in a wind-prone area. Remember to loosen ties on nursery stock before they girdle the trunk. Gently secure any tree requiring staking with two opposing flexible ties on the lower half of the tree, allowing the tree to gently blow in the wind to encourage lower trunk strength. Avoids staking trees tightly, restricting flex. As the tree matures, remember to loosen ties with the goal of removing stakes entirely if the tree becomes self-supporting.
Pruning. Avoid heavy pruning at the time of planting. Remove only broken branches, crossed branches and suckers at the base of the tree. Don't top your trees! (More on this next month.)
Fertilizing. Most trees have received adequate nutrition in the nursery and do not need fertilizer at the time of planting.
Mulching. Apply a 2-4 inch layer of mulch three or more inches away from the tree trunk. Organic mulches such as woodchips and compost should be applied and maintained at a depth of 3-4 inches to prevent weed seeds from sprouting. Inorganic mulches (gravel, pebbles, etc.) should be maintained at 2-3 inches. In fire-prone areas, organic mulches near the urban/forest interface should be avoided. Remember to irrigate below the mulch.
For more information on tree planting and care and all other home gardening and landscape topics, contact the UCCE Riverside County Master Gardener helpline here in the Coachella Valley: anrmgindio@ucanr.edu
