Landscape professionals understand that trees have tremendous value and offer many benefits: trees prevent soil erosion and water pollution, provide shade for homes and habitat for wildlife, and increase property values. But consumers need ongoing education and reminders of the role trees play in the health and beauty of communities.

Consumers also need ongoing education about what trees are appropriate to grow in Colorado’s conditions and how to care for them. Across the state, arborists and other tree care professionals continue to encourage tree diversity in age and species in order to avoid monocultures or disrupt those that may exist.

Many landscape professionals continue to recommend following the 10-20-30 rule proposed by the late Frank S. Santamour, Jr., of the US National Arboretum, in 1990:

For maximum protection against the ravages of “new” pests or outbreaks of “old” pests the urban forest should contain:

• No more than 10% of any single tree species.
• No more than 20% of species in any tree genus.
• No more than 30% of species in any tree family.

Development brings unrealistic expectations
Steve Geist of SavATree, Denver, noted that many homeowners “look for something that will establish and grow quickly, [and is] low maintenance and with minimal debris” yet they want trees that produce a fall color display.

“Those characteristics don’t match up,” he said. “Colorado’s plant palette has a narrow band, and the hardiness zones don’t tell you the full story. With increased frequency, we are experiencing fall and winter freeze events making several trees that were once hardy in eastern Colorado, now somewhat unreliable.”

Those unrealistic expectations have resulted in what some consider overplanting of some species. Autumn Blaze maple, readily available at nurseries and big box stores, provides the red fall color that homeowners—especially those who have settled in Colorado from other regions—romantically imagine in their ideal landscape.

Several arborists told Colorado Green that they encourage clients to consider other species to avoid significant tree loss should newly planted trees fail or fall prey to a pest in the future.

Tree pros also encourage both consumers and landscape architects and designers to adjust their expectations and opinions on what constitutes a healthy, attractive landscape in Colorado. They hope people can embrace the look of plants that are well-suited to the region and resist planting trees that won’t thrive.

This article originally appeared in the March/April issue of Colorado Green magazine. Read the full article in the digital edition.

Read more in this issue of Colorado Green NOW:
2020 CSU flower trials top performers
COVID vaccines: implications in the workplace
Days on the Hill to be virtual for 2021
Spring is a good time to review your safety plan