Street Tree Recommendations for the Western Valleys of the Pacific Northwest
Why This Is Important and How It Affects YOU
The following list of recommended columnar or semi-columnar street trees for the western valleys of the Pacific Northwest is the convergence of several efforts on the author’s part.
This list is the distillation—the crème de la crème—of the analysis of numerous varieties of street trees from various lists compiled by numerous people, organizations and local municipalities. The best choices, in the author’s opinion, have been carefully selected. (More suitable street trees are being added to the list as they come to the author’s attention. So what makes the author’s opinion worth anything? Glad you asked.
Nathan Lawrence, ISA Certified Arborist and a second-generation Pacific Northwest arborist and horticulturist who has been earning a living caring for trees in Northwest Oregon since 1972, has put this list together based on long experience dealing with countless varieties of trees and learning how they react in numerous situations including wind, rain, ice, snow, blights, drought, attacks from pests, construction trauma, lightening, poor growth habits, structural failures, human neglect and more.
While owning and operating a tree care company in Northwest Oregon since 1985, we have encountered hundreds if not thousands of street tree situations. We have seen it all from the trees’ roots to top of a trees’ crown and all points in between. Nathan know the odor and even the taste of trees. He has seen the damage that misplaced trees can do to foundations, sidewalks, driveways, walls, houses, cars, near fatalities due to limb breakage and trunk failures, destroyed street lights, impacted utilities, plugged sewer pipes and busted water meters and pipes, and more.
Sadly, we have had to remove thousands of trees that were the wrong tree in the wrong place. Had an ISA Certified Arborist, like Nathan, been consulted prior to planting these trees, many removals of glorious, life-giving trees without which life on earth would cease could have been preserved simply by planting the right tree in the right place. In fact, nearly all the street trees in the cities where we work are the wrong ones; they are the wrong tree in the wrong place! We see municipalities all using the same (wrong) trees over and over again. These include red maples, Norway maples, callery pears, flowering plums, raywood ashes, pin oaks, and other trees that are too large for the areas in which they have been planted.
It is the sincere desire of this life-long arborist, who climbed his first tree at age one, that somehow this list of recommended street trees will help to insure that street trees, if properly planted, will last for generations and be spared the arborist’s chainsaw due to careless planning and planting habits.
Growth Rates of Popular Ornamental Trees (Generally Suited for Zones 5 to 8)
Growth rates of all ornamental trees will vary depending on variety, climate and soil conditions, the amount of water they receive and other biological and environmental factors. The growth rates listed below are for climate or hardiness zone 8 where winter temperatures are seldom below 10 to 20 degrees Fahrenheit. Many of the trees on this list can easily survive at zone 5 temperatures (-10 to -20 degrees Fahrenheit).
How and Where to Plant These Trees
The following list of trees is suitable in parking some strips along streets, in front yards, in parking lots, in front of retail buildings or any other spot where height, not width is needed. It must be stated that the size of the parking strip must determine the size of the tree planted therein. Basically, small trees must be planted in narrow parking strips and larger trees can be planted in larger strips. LARGE TREES CANNOT BE PLANTED IN SMALL PARKING STRIPS! Period. It doesn’t work. It causes damage to infrastructure, which costs everyone lots of money. It just causes grief for everyone, and enriches the coffers of the arborist who has to eventually remove the tree.
All of the trees on this list will take full sun, need moderately well drained soil, and will need watering for at least the first three seasons after being planted until their roots are established. After that, they will need little if any extra watering during the summer season, unless otherwise noted.
All of these trees are relatively low maintenance, are not overly messy (except when dropping their leaves), are structurally stable (in most cases), and are, for the most part, disease resistant.
It is important to plant a tree properly. This involves much more than digging a hole and planting throwing the tree into it and tossing the soil back in. To protect your investment, plant the tree properly and at the right time of the year. The best time of the year to plant trees is from November to February when the trees are dormant—when it’s cool and cold. Trees can be planted anytime of the year if done properly. Arborist and landscapers successfully plant trees all year long. When planting a tree during the growing season (March through late-September), extra care has to be taken to ensure that the tree is irrigated regularly, or else it may die. To learn how to plant a tree properly go to https://www.arborday.org/trees/planting/containerized.cfm or https://www.treesaregood.org/treeowner/plantingatree.
Trees need to be planted properly in good soil. Add organic matter amendment to the soil if planting in heavy clay. After the tree is planted, water well at the time of the planting. Afterwards, deep water (so that the deepest tree roots are saturated—regular lawn irrigation isn’t usually sufficient to accomplish this) it at least once a week during warm weather, and twice a week during hot weather for the first three seasons. Additionally, add a circular, lawn free tree ring covered in mulch (such as barkdust or wood chips) that is at least three feet (five or more feet is even better) out from the trunk and two to four inches deep. This will help to keep mowers and string trimmer from damaging the trunk, and will help to keep water in the root zone during hot weather. A tree ring also reduces harmful soil compaction from foot traffic at the base of the tree. A tree ring will also act as a deterrent against weeds, which compete with the tree for water and nutrients.
Shallow tree roots can cause problems for lawn and landscaped areas. Remember this. The shallower the topsoil, the more likely the roots are to grow on the soil’s surface. They might even protruded above the grass. The larger the tree, the larger the roots. Additionally, the closer a tree with large roots is to hard surfaces (e.g. patios, sidewalks, brick walls, foundations or driveways), the more likely it is to grow into or under and potentially (eventually) lift and crack these hard surfaces. The further one can plant trees away from hard surfaces the better, and the less likelihood there is of roots causing damage.
Always plant trees away from underground utilities—especially water meters and lines. Also, plant trees that grow taller and wider away from street lights.
Good News Tree Service, Inc. of Wilsonville, Oregon has a comprehensive list of more than 125 street and yard trees categorized according to size with descriptions. This list is available to our paying customers, and includes varieties such as flowering cherry, beech, crabapple, dogwood, hornbeam, maple, oak, zelkova and many more.