So, you want to plant a tree? It’s April in the Mile High City, and…
Part of what makes Denver a great place to live is its altitude and climate. But did you know that because Denver is located in the high plains, our ecosystem is home to very few large, deciduous tree species? These are the trees that make our city shady and provide us with benefits like improving air quality and combatting heat islands. In this blog post, we’ll give you tips on the best trees to plant for Denver’s climate and how these recommendations help our urban canopy.
While Denver’s Office of the City Forester wants all Denver residents and property owners to plant more trees and help grow our urban tree canopy, some trees are simply better equipped than others to survive in our unique climate. And while it’s important to plant new trees here in the city, it’s even more important that those trees survive. To make it easy for you to choose an appropriate tree, we’re providing this handy list of the what’s and why’s for our climate, and which trees are not only best suited to survive, but to thrive, in Denver.
What makes Denver’s climate challenging for trees?
There are two primary factors that make it challenging for some large trees to thrive in Denver:
- Soil: Colorado soils generally have adequate to high iron levels, as evidenced by the many red soils and rock formations. However, Colorado soils are mostly alkaline, causing most of the iron to be in a form not usable by plants.
- Water: Denver is also a semi-arid climate, meaning we get some precipitation but not much. Young trees need consistent watering here to establish and thrive, especially during periods of drought and high temperatures.
Which are the best trees to plant in Denver?
Which trees are most likely to thrive in our climate? Here’s our top 8 trees to plant:
- Kentucky Coffeetree (large): The Kentucky Coffeetree adapts well to a wide range of soils and urban environments. Its drought and pollution tolerance makes it a great choice for city living, particularly in Denver’s arid climate.
- Common Hackberry (large): A shady tree with a widespread crown that turns yellow in the fall, the Common Hackberry is native to North America and withstands winters sturdily.
- Northern Catalpa (large): The Northern Catalpa is drought tolerant and grows well in alkaline soil with its large heart-shaped leaves and white flowers in the springtime.
- Bur Oak (large): One of the oak tree varieties, the Bur Oak’s most prominent feature is the acorns it grows. It’s often planted in Colorado where it thrives in our climate and soil.
- Turkish Filbert (medium): Tolerant of a wide variety of soil conditions, the Turkish Filbert’s leaves turn yellow in the fall and may produce small nuts.
- Thornless Cockspur Hawthorn (small): Covered in white flowers in the spring and persistent fruit through the winter, this small tree grows horizontal branches and provides food for birds.
- Autumn Brilliance Serviceberry (small): Known for its pretty white flowers in the spring, this small tree is a relatively low maintenance tree and great for attracting birds and bees to your yard.
- Amur Maackia (small): A shapely, small tree with beautiful red fall color, the Amur Maackia is very hardy and adaptable to Denver’s climate.
All of these trees are commonly planted through our free tree program. If you have room in your public right-of-way, an arborist will visit your site and make a recommendation for what kind of tree may thrive there.
The Front Range Tree Recommendation List, developed by Colorado State University, is also a helpful resource for seeing how various tree species rate based on the factors of our area. Keep in mind this publication was released in 2010, so while ash trees are included, because of the threat of emerald ash borer, the planting of ash trees is no longer permitted.
What trees don’t do as well here?
Although beautiful trees that everyone wants on their properties, a few trees shouldn’t be planted in Denver because they’re less likely to thrive in our climate. Here are two to avoid:
- Maples: Maple trees include a number of species that are known for their vibrant colors and notable leaves. However, maples are susceptible to chlorosis, or leaf yellowing due to insufficient iron. This happens often to maples here in Denver due to our alkaline soil. Maples also have thin bark which makes young trees especially susceptible to damage due to sunscald. And finally, maples are not very drought tolerant, which can be a challenge in our semi-arid climate.
- Aspens: Aspens are native to higher altitudes, which is why we all make trips to the mountains to see their fall color. They thrive in areas that aren’t as hot and have different soil conditions than we have here in Denver. Aspens in the metro area are more susceptible to pests and diseases and have inherently shorter lives.
How do I navigate the conversation with my landscape professional on what to plant?
It’s always best to show up informed to a meeting with your landscape professional. Bring this article, the Front Range Recommended Tree List or the Forestry-Approved Street Tree List to help guide you. In addition to coming informed on what trees are best for Denver’s climate, you should also show up with an idea of what tree values are most important to you:
- Shade – look to large species with dense canopy
- Aesthetic – look for species that flower/you enjoy the look of
- Wildlife – look for species that provide fruit/flowers for wildlife/pollinators
- Xeriscape – look for more drought tolerant species
- Space – limited space requires ornamental or medium sized trees
Make sure your landscape professional is considering sunlight, soil, irrigation, surrounding tree diversity and distance from structures and other trees to pick the best tree for your location.
Above all, just remember the mantra, “right tree, right place.”