Many urban trees now only live about 20% of their life
Many urban trees now only live about 20% of their life expectancy due to issues like drought, pests and disease, but mostly because of improper care and installation.
A tree should live more than 50 years, and up to 100 years depending on their species. A recent USDA study analyzing tree life expectancy in urban areas finds the typical street tree living between 19-28 years; however, the ideal life span of a California oak is 600 years, and the average life span of Douglas fir and most Pine trees can be between 75 to 150 years in Southern California.
Urban tree planting has increased
Urban tree planting has increased in response to residents’ lack of interaction with nature and the benefits these trees provide the environment through services like cooling buildings with their shade and cleaning the air and water through filtration.
However, urban trees must withstand the drought, pollution, poor soils, limited leg room for roots, and pressure from insects and disease, and their health and cultural requirements are not considered or monitored.
Maybe it’s these urban challenges that cause them to die young; what’s worse, most are planted incorrectly, giving them a poor outlook from the beginning.
Basic knowledge of tree planting can help your urban tree live longer.
However, some basic knowledge of tree planting can help your urban tree live longer. We have 50 years of experience an trained Arborists to advise you.
1) Right tree, right placement.
It is essential that certain growing parameters be considered when choosing what type of species tree to plant. Answer the following questions to choose the right tree.
What are the attractive characteristics? Is the tree deciduous or evergreen? What are the cultural requirements of the tree (sunshine, soil, water and climate)? What is the soil pH and the soil type (well drained or compact)? Does the site get full sun or partial sun? How much water does that tree need? What is the growth rate of the tree? What kinds of things does the tree tolerate (salt, drought, flooding)? What are the insect and disease issues that tree is susceptible to? What are the planting needs and pruning needs of the tree? Can the tree thrive in areas that restrict root growth?
2) Space your trees properly for their mature size.
Small trees that grow 10 to 30 feet tall need a twenty-foot diameter. Medium sized trees that grow 30 to 50 feet tall need a thirty-foot diameter. Large tees that grow taller than fifty feet need a forty-foot diameter. Many homeowners make this mistake by planting a small sapling close to their house only to cut it down later, or over-prune, interfering with the natural shape of the tree.
3) Plant trees at the right depth.
Trees planted too deep look like telephone poles because their natural root flare cannot be seen above the soil line. This strangles the roots below the soil. A proper planting hole is two to three times wider than the root ball and no deeper. (Rough up the sides of the hole with your shovel so roots will spread easier.) Place the tree so the root flare is at or just above the soil line. Sometimes, the tree is planted too deep in the container or root ball it comes in. It is essential that you dig a little to find the top root, and plant at that depth. Avoid amending soil, as roots won’t expand into the less favorable soil.
4) The best thing for a tree in an urban environment is pruning.
The worst thing you can do is improper pruning. Topped trees and stubbed branches weaken new growth and create an avenue for insect and disease. Proper pruning allows strong structural growth, protection from wind, and reduces the risk of tree failure.
The reason urban trees need to be pruned vs. forest trees is that they grow massive side branches, which are usually shaded out in a forest environment. Start corrective pruning the second season of your tree’s life.
5) Use mulch from local trees
Use mulch processed from local trees and avoid rock and artificial mulches. Mulch two to four inches deep as wide as you are willing to go. Properly mulched trees will require less irrigation, less competition with grass roots, and keep trees safe from lawn mower damage.
6) Strangling roots
Strangling roots (commonly called girdling roots) circle the base of the tree rather than spreading out, providing a weak anchor and and cutting off the sap flow to the stems and leaves. These trees will decline and die within five to twenty years. Girdling roots are caused by improper planting, obstructions like sidewalks and curbs, and poor soils.
Signs of girdling roots include: absence of a trunk flare at ground level, leaning trunks, bark cracks, branch dieback, and leaf issues. Data collected at University of Minnesota concluded that a third to half of the trees that fall after a storm can be attributed to girdling roots. It is much easier to prevent girdling roots rather than fix them when tree starts showing signs of decline. At planting, cut off circling roots, follow good planting practices and monitor tree to avoid girdling roots in the future. Some tree species are naturally prone to girdling roots like ash, pine, and oak.
7) Tree Staking
Do not stake your tree unless you have to, and remove them after one season. Only use staking materials if wind is an issue at the site, or to protect from vandalism. Staked trees do not grow strong, develop poor root systems, and suffer from rubbing against their support system.
Learning basic tree care from Flintridge Tree Care you will be increasing the life of your trees and ensuring that they will outlive you, a gift to the next generation.