Don’t Plant These Trees in Your Urban Yard
Author: Mary Boone
Choosing the best tree for your urban backyard is a tough decision. Make a bad choice, and remorse will be yours for years to come.
While it’s true that many trees can add beauty, privacy and shade to your property, others have the potential to wreak havoc thanks to invasive root systems, prickly thorns, messy fruit or weak branches.
Before planting, take the time to do some research. What do you want your tree to do? Are you most interested in shade? Blocking a view? Adding color to your landscape? How much space do you have and is growth rate important to you? Deciduous trees lose their leaves in the fall and are bare all winter. If you want foliage throughout the year, you’ll need to select an evergreen, such as holly, hemlock or spruce.
Sharon Lilly, director of educational goods and services at the International Society of Arboriculture, cautions against labeling any tree as “bad.”
“Every tree has advantages and limitations, and there is a right place and a wrong place to plant them,” she said.
When you’re thinking about the perfect tree for your urban lawn, here are a few that you probably should avoid:
Weeping willow (Salix alba v. tristis)
These graceful, flowing trees might seem like the perfect addition to any landscape, but be warned: Weeping willows require continual care because of brittle wood, which causes broken branches. They are very susceptible to breaking in a storm and smashing whatever car is parked beneath them. They are beautiful trees, but require a very large growing area — not just for their width and height but also because their root systems can be quite invasive.
These trees are generally so weak and unstable that even mild storms can cause branch failures. While the trees’ invasive root systems and branch shedding habits can be beneficial in rural and forested settings, they’re not a great choice in urban areas. Their size is often overwhelming, they give off a urine-like scent, and their fast-spreading root systems can crack foundations and sidewalks. Cottonwood trees have been banned from planting within many U.S. neighborhoods and cities because the “cotton” from them clogs filters and is generally untidy.
Russian olive (Elaeagnus angustifolia)
This deciduous tree has been identified by the U.S. Department of Agriculture as an invasive species for its tendency to crowd out native plants. Homeowners often complain about a rusty staining of driveways and sidewalks located under a Russian olive tree’s thorny canopy. Researchers have learned the staining is not caused by the tree’s fruit or foliage, but instead is the result of arthropod infestations.
Norway maple (Acer platanoides)
“Aside from being overplanted and invasive, these trees will often get ugly looking tar spots on their leaves,” said Daniel Jost, an editor at Landscape Architecture Magazine. “These spots won’t kill the trees, but they’ll disfigure them so badly that you’ll wish they were dead.” The Norway maple usually grows too large for a residential yard, and its shallow root system can lift and buckle sidewalks, patios and roadways.
Ash trees (Fraxinus spp.)
“Sadly I would discourage anyone from planting a new ash tree in their yard,” Jost said. “While these trees have beautiful fall color, an invasive insect called the emerald ash borer is making its way across the U.S. and killing large numbers of ash trees in its wake. It’s killed tens of millions of trees in southeast Michigan already.”
Callery pear (Pyrus calleryana)
Because of their beautiful white flowers, Callery pears were widely planted across the United States in the 1960s and 1970s. Unfortunately, those pretty white flowers have a bad odor, and some of the cultivars (including Bradford) have poor branching structure and became known for dropping branches during storms. These trees are known to be invasive throughout much of the Northeastern United States.
The exact same tree all your neighbors have
“We have been very slow to learn our lesson when it comes to planting a diversity of trees,” Jost said. “In the 1950s, many of the loveliest neighborhoods in the country were shaded by double rows of elm trees and only elm trees. When Dutch elm disease ravaged these neighborhoods, it killed nearly every single tree and left these places desolate. Cities that replaced all their elm trees with ash trees are facing a similar dilemma today thanks to the emerald ash borer. By planting a diversity of species, we protect ourselves against the risk of an unexpected disease. Just like we diversify our investment portfolios, we need to diversify our urban forests.”
Trees that need lots of irrigation
“If you are living in the desert Southwest, Southern California or some other region with tight water resources, you should avoid planting trees that have high water needs,” Jost said. “In some places, including most of Las Vegas, it is not possible to plant a tree without some irrigation. But you should choose a tree with lower water needs like a mesquite or a palo verde.”
Any tree that has circling roots
When you buy your tree, check to see if the roots are circling inside the pot. These roots probably won’t affect your tree immediately, but as the tree ages, those roots can wrap around the base of the trunk and restrict the flow of water and nutrients. A tree with circling or girdling roots seldom survives more than a decade in the landscape.
A tree that is not allowed by your community
Many communities and homeowners associations have lists of trees that you can and cannot plant. Take the time to understand your community’s rules. Otherwise, you may be fuming when you have to pull the tree out.