Arboretum at CSU
Campus Arboretum Committee Overview
The Campus Arboretum is overseen by the Campus Arboretum Committee, which includes representatives from Facilities Management, the Department of Horticulture & Landscape Architecture, CSU Extension, Plant Select, and the City of Fort Collins Dept of Forestry. The Colorado State Forest Service joins in during Tree Campus Higher Education activities.
View our CSU Tree Genus Species List.
View our Collections Management Manual.
View our Tree Care Plan.
ArbNet Level III Arboretum
The Colorado State University (CSU) Campus Arboretum and Botanical Garden embodies CSU’s land-grant heritage and mission by offering an engaging learning laboratory environment for students, employees, and community visitors. We manage trees diverse in terms of age (from newly planted to 140 years old), class, and species (approx. 300 species), distributed over three campuses (Main, South, and Foothills), comprising 2,400 acres of land. The largest trees have up to a 69” diameter at breast height (DBH), with an average trunk diameter of 10.65 inches. The most common CSU main campus tree is honeylocust (9.78 percent), followed by green ash (8.83 percent), blue spruce (7.15 percent), Rocky Mountain Juniper (5.72 percent) and Austrian pine (5.22 percent). We are actively and intentionally working to establish better species diversity, so our overall campus forest will be more resilient to invasive pests, climate change, and severe weather events.
The majority of CSU’s managed urban forest is located on the Main Campus within 220 acres of irrigated landscape. The Campus Arboretum leverages the investments of our historical and diverse urban forest, the Heritage Arboretum and Garden, CSU Horticulture Research Center, Annual Flower Trial Gardens, and the Perennial Garden at the University Center for the Arts. The CSU Campus Arboretum is an exceptional asset for the community, advancing individual programs and efforts around research and teaching through the overarching structure and prominence of the arboretum, while solidifying a legacy that preserves our urban forest for future generations.

ArbNet’s Arboretum Accreditation Program advances the planting, study, and conservation of trees, recognizing arboreta at various levels of development, capacity, and professionalism and fosters professionalism of arboreta worldwide. No other international program of accreditation exists specific to arboreta. Accreditation is based on self-assessment and documentation of an arboretum’s level of achievement of accreditation standards, including planning, governance, number of species, staff or volunteer support, education and public programming, and tree science research and conservation. Learn more about CSU’s ArbNet Accreditation Level III status and the Morton Register.

Tree Campus Higher Education
We held our 2025 Arbor Day celebration on April 23rd, planting six trees between the Visual Arts and Chemistry buildings. This was our 15th consecutive arbor day planting, and our 14th year being acknowledged as a Tree Campus Higher Education institution.
To be a Tree Campus Higher Education community, CSU ensures the protection and maintenance of our campus urban forest, reduces hazardous tree risks to public safety, and maintains a sustainable campus forest through tree species diversity and best management practices. The university joins more than 150 American colleges and universities recognized by the program. Specifically, Facilities Management and the Colorado State Forest Service team up to meet the five Tree Campus Higher Education standards: Campus Advisory Committee, Campus Tree Care Plan, Campus Tree Program with Dedicated Annual Expenditures, Arbor Day Observance, and Service Learning Project. Throughout each year, the Tree Advisory committee meets to ensure that the Tree Care Plan stays current and addresses new challenges as they arise. Each spring, they host an Arbor Day celebration, which provides students with a hands-on opportunity to learn more about trees and their important role in our environment.
CSU’s Campus Arboretum has 10,000 trees that make our community more resilient and healthier. They clean our air and water, help manage storm water runoff, prevent soil erosion, provide habitat, sequester and store carbon, reduce noise pollution, and cool buildings and walkways with their shade. But they’re not just function first. They also boost personal and public health, give us places to relax, play, and study outdoors, and add color and beauty to campus. Thanks for taking a moment to celebrate Arbor Day and appreciate the value that trees bring to our community!
More tree resources available by visiting the Colorado State Forest Service at Facebook and Twitter or CSU Extension (facebook.com/extensioncolorado).










Resources about Trees:
Trees in the West
Conference Overview
May 20, 2025
8:30 a.m. to 4 p.m.
CSU Spur, Denver
All About Trees (2023)
Recorded: Friday, May 5, 2023
Instructor: Eric Hammond, Adams County Extension
Recording: https://youtu.be/TgTNT3Uwrxc
Celebrate Trees for Arbor Day! (2022)
Recorded: Friday, April 15, 2022
Instructors: Cassey Anderson, Eric Hammond, Amy Lentz, Lisa Mason, and Alison O’Connor, CSU Extension
Recording: https://youtu.be/jXNfIOxGuUA
Tree Planting (2021)
Recorded: Wednesday, April 14, 2021
Instructor: Alison O’Connor, Larimer County Extension
Class recording: https://youtu.be/n_Ek0CLJ7mI
For more classes like this, visit the CO-Horts Blog to find upcoming and past recorded trainings!
Campus Tree Tour
CSU’s Notable Tree Tour on Main Campus is a self-guided tour of 15 signature trees including three notable campus tree collections at the Oval, Sherwood Forest, and the Heritage Arboretum. In 2021 the Campus Arboretum Committee received funding from the President’s Sustainability Commission sustainability fund to place 15 interpretive signs by the trees on the tour. Check out the tour by visiting the CSU interactive map and choosing the Tours tab.
Special Tree & Plant Collections
Perennial Garden
In the fall of 2016 the Perennial Teaching, Research, and Demonstration Garden was relocated from the old Plant Environmental Research Center (PERC) to its new home next to the CSU University Center for the Arts on Remington and Pitkin. The Perennial Garden was originally started at the PERC site in 1980 by Dr. Jim Klett and has grown over the decades to approximately 1000 taxa. Three of each taxa were moved to the new location for a total of approximately 3,000 plants. In addition to the 3,000 herbaceous perennials moved, 19 trees were saved and relocated.
Heritage Arboretum & Garden
The Heritage Garden & Arboretum Collection is 5.5 acres and was established over thirty years ago. It has the largest collections of woody plants in the region with over 1,100 different taxa represented. The Heritage Gardens showcase the agricultural heritage from six major regions in Colorado. Presently, a computerized method for collection, storage, and retrieval of information on plant performance has been implemented for all the woody plants. New plants are continually being added to and evaluated in the collection.
Read the Heritage Arboretum reports or learn more about woody plant research: http://woodyplants.colostate.edu/
Centre Avenue Arboretum
The main objectives of this area are to determine which woody plants are best suited for growing in the Rocky Mountain area and display these plants for public research and teaching purposes.
It began in 2003 with the need to relocate some trees at the Heritage Arboretum when the Summit Hall dorm was constructed. The trees were moved to the Centre Arboretum site which is approximately 6 acres. The plants at both the Heritage Arboretum and the Centre Arboretum are now part of the overall campus arboretum effort but are still managed by the Department of Horticulture and Landscape Architecture. Both areas have plants that were donated to the woody plant evaluation program from generous support from members of the Green Industry and other public gardens. Between the two sites, the arboretum at CSU has the largest collections of woody plants in the region with over 1,100 different taxa represented. Each plant is evaluated every two years and the report is available for free and online at http://woodyplants.colostate.edu/. New plants are continually being added and evaluated in the collection.
The plants at the Centre Avenue Arboretum are strictly trees while the Heritage Arboretum also includes many shrubs. The other main difference between the two sites is that the Centre Avenue site is organized in straight rows with a drip irrigation system while the Heritage site is planted in a more informal pattern by plant family and is irrigated with hoses and sprinklers. Both areas have each plant labeled with both scientific and common names and the label is usually on the north side unless there is a compelling reason (such as crowded by a nearby plant) to have it on the east or west. Both sites are free and open to the public during daylight hours.
Annual Flower Trial Garden
The outdoor display and test areas at the Annual Flower Trial Garden were established to allow students, researchers, industry representatives, homeowners and extension personnel to learn, teach and evaluate through horticultural research and demonstration projects conducted in the unique environmental conditions of the Rocky Mountain/High Plains region.
Read more about the Flower Trial Gardens: http://www.flowertrials.colostate.edu/
The Oval
The Oval elm collection dating from 1881, is preserved for the long-term benefit of university and has continuing research value in finding efficacious treatments for evolving exotic pests of elm.
Fun Facts & History:
When were the original Oval trees planted?
- The center double row of trees (the tree allee) were originally planted in 1881 as part of a larger tree planting effort on campus. This was almost 30 years before the Oval as we know it today was proposed as part of the 1910 Master Plan by W.W. Parce, a landscape architect with an office in Boulder. Most of these 1881 trees survive today, but many have been replanted over the last 137 years, and are now of equal size with the originals.
- The Elm trees ringing the exterior of the Oval were planted between 1922 and 1927 in successive annual plantings. Many of these trees are now larger than the original 1881 planting.
What kinds of trees are in the Oval?
- Almost all of the trees are American Elm – Ulmus americana
What differences are there between the original trees and the trees planted today?
- It is apparent that the plantings of 1881 and of the 1920s were seedling American Elm, and unlike the clonal varieties of American Elm sold in the nursery trade today, each is genetically unique. As a result, some of the trees have unique characteristics, and some tree lovers would say personalities.
What impacts have there been to the health of the Oval trees over the years?
- The Oval trees have survived many fall and winter ice and snow storms largely intact, but there were two periods of extreme crisis, which could have resulted in the loss of the Oval elms that exist today.
- Dutch Elm Disease (DED) was an extreme risk to the Oval starting in the 1970s when the disease arrived in Colorado. Without active intervention, including a sanitation protocol, Dutch Elm Disease is fatal, and by one account of the estimated 77 million elms in north America in 1930, 75 percent were lost by 1989. Most of the Oval trees have survived Dutch Elm Disease, but there have been loses over the years, even in the last 15 years. The Elms are monitored for signs on the disease, and if the disease is confirmed the tree is immediately removed and isolated from adjacent trees by trenching around the infected trees. The trees are of such size, that their roots are intertwined and likely grafted together in places allowing the disease to be spread from tree to tree.
- In the 1990s a study identified the Oval Trees as being in decline. A lack of funding for ongoing maintenance and the use of the Oval grounds for multiple events during the school year and summer had placed the trees in vulnerable state. The trees were suffering from equal parts neglect and the overuse of the turf which contributes to soil compaction which is directly related to tree heath. A steering committee was brought together to recommend a new plan for the Oval, public meetings were held, and emotions ran high as two competing visions emerged. One vision called for the removal of all Oval Trees and a replanting of 98 elms in their original positions to maintain the original Oval pattern. A second vision called for the addition of multiple species of trees in an irregular pattern to be planted over time to give the Oval both species and age diversity, while maintaining existing elms, but replanting them in the original pattern. In the end neither vision was implemented, and 20 years later the Oval trees are arguably in a more sustainable state that they were 20 years ago, and the Oval remains the most iconic space on campus.
What recent efforts have contributed to the success of the Oval?
- Holding events regularly on the Oval had accelerated compaction of the soil; therefore, the elimination of non-CSU events (such as Taste of Fort Collins and an annual Dog show among others) from the Oval grounds and limiting other events has helped to manage and mitigate compaction.
- No structures are allowed to be built on the Oval, including benches, and nothing can be hung from the branches of the Oval trees.
- The Oval is free of lighting and electrical receptacles, and although it is sometimes suggested that holiday lights be hung from these trees, the extensive trenching needed to bring power to each tree would likely kill or significantly shorten the lives of these trees.
- Trees are annually treated to control a scale insect that saps the strength of the trees.
- Trees are continually monitored for Dutch Elm Disease during the growing season.
- Dutch Elm resistant, and scale resistant elms have been planted when older elms are lost, maintaining the historic Oval tree pattern.
- All of the Oval elms are pruned on a three-year interval for tree heath, and safety of the campus community.
How much does it cost to sustain the Oval trees?
- On an annual basis it costs more than $50,000 to sustain the Oval trees. Annual treatments for insect (scale) control is $30,000, and the last three-year cycle of pruning cost $130,000. The Oval Preservation Fund proceeds go directly towards these costs, but cover only approximately 10% of costs on an annual basis.
What is the Oval Preservation Fund?
- Primarily it is a vehicle to preserve the existing Oval Elm trees in a safe and healthy condition for future generations. As these historic trees are lost through extreme age, disease, or storm damage, the Oval Preservation Fund helps to plant new Elm trees in their places to insure the Oval composition endures into the future.
SOURCE – Oval Trees 101: Do you know their history? (October 18, 2016)
Arboretum News & Media
CSFS News – Forestry Students Calculate Economic Benefit of Campus Trees to Celebrate Arbor Day (April 19, 2024)
CSFS News – CSU Recognized as Tree Campus-Higher Education for 12th Consecutive Year (April 27, 2023)
SOURCE – Literally just 46 facts about CSU’s trees (April 19, 2022)
SOURCE – CSU community to plant 12 trees in celebration of Arbor Day (April 11, 2022)
SOURCE – CSU marks 10th straight year of being honored as Tree Campus Higher Education Institution (Sept 22, 2021)
SOURCE – Emerald Ash Borer on the move along Front Range by CSFS (May 25, 2021)
SOURCE – Celebrate Arbor Day and Earth Week with CSU (April 20, 2021)
SOURCE – 150 New Trees Celebrate CSU’s Sesquicentennial (April 20, 2020)
ALUMLINE – The Oval: Preserving A Living Legacy (April 06, 2020)
SOURCE – CO Woody Plants: An Arboretum in Your Palm (July 12, 2019)
The Collegian – CSU receives 8th Tree Campus USA award at tree planting event (April 21, 2019)
SOURCE – Volunteer tree planting to focus on ‘Right Tree for the Right Place’ April 19 (April 15, 2019)
SOURCE – Campus community helps fund tree planting event (April 20, 2015)
SOURCE – Favorite Tree Campus USA (Nov. 03, 2014)
CSU is a proud member of the American Public Gardens Association, ArbNet, and Tree Campus Higher Education.
For more information about the Campus Arboretum or Tree Campus Higher Education, please contact Julia Innes via CSU email.
To locate the CSU main campus or get directions, view the CSU interactive map.






