Multi-site Woody Plant Evaluation in Colorado
Eric Hammond and James E. Klett
Department of Horticulture and Landscape Architecture
Objective and Justification of this Project
Plant introduction programs such as Plant Select ® have a goal of promoting and introducing superior woody plants to the public. Currently, little research data is collected in a manner that is both timely and representative of conditions in different Colorado regions. There is no existing multi-year, multi-site, systematic, coordinated woody plant evaluation program in Colorado. This project utilizes multiple research sites throughout the state to evaluate woody plants in order to present a more reliable and accurate pool of information regarding plant performance in this region. Each plant taxon will remain in the study at least three years. In addition, we are introducing new plants into the trial each year. The purpose of this study is to enhance the palette of woody plants available for Colorado landscapes, and to determine that these plants can be produced in quantities and in timeframes making them profitable to grow here. Nursery propagators, growers, university researchers, and plant brokers have all provided input in determining the list of plants which merit study. They are grown in a coordinated effort at research facilities and cooperating nurseries.
Selected trees and shrubs were grown in field trials at multiple sites throughout Colorado.
Significance to the Industry
Information from this program will assist members of the Green Industry by targeting woody plants which merit further study. Again, industry representatives and university researchers were directly involved in composing this list. With the information gained from this research, Plant Select® can work hand-in-hand with local growers to assure that the species or cultivar is a superior plant worthy of promotion in Colorado. When this plant is promoted, the nursery industry will have an adequate, locally grown supply to meet anticipated demands.
Colorado State University continued work with woody plant evaluation throughout 2010. Working with Plant Select®, researchers and industry representatives maintain a listing of plants unused or underused in Colorado landscapes. These plants have multiple ornamental features, and seasons of interest. There are four co-operating sites, including three private sector nurseries, Harding’s Nursery (Calhan); and Little Valley (Brighton). In addition, two Colorado State University research sites, the Horticultural Research Center, Fort Collins, and Western Slope Research Center, Orchard Mesa, at Grand Junction, are participating. There are eightreplications of each plant at each site, planted in a randomized block arrangement.
– Nursery propagators, growers, university researchers, and plant brokers provide input to determine a list of plants which merit study
– Eight individuals of each plant are planted at each of four sites (32 plants total)
– Plants remain study for five years
– Growth size and overall performance data is gathered at regular intervals
Introductions and Successes from the Trials
Cupressus arizonica ‘Cooke Peak‘ (Cooke Peak Arizona cypress)
– Aromatic blue green foliage
– Cold hardy to -30ºC
– Alternative to traditional conifers
Acer tataricum ‘Gar-Ann’ (Hot Wings® Tatarian Maple)
– Small Tree
– Good fall color
– Good branchangles
– Striking red fruit present throughout the summer
Heptacodium miconoides (Seven-son Flower)
– Large shrub/Small tree
– Fragrant white flowers late summer
– Red sepals in fall
– Exfoliating bark
– Excellent specimen plant
Xanthoceras sorbifolium (Yellowhorn)
– Small tree- up to 20ft tall
– White flowers with maroon eyes April to May
– Leathery seed pod persisting into the winter
Potential Future Introductions
Juniperus scopulorum ‘Woodward’
Quercus muehlenbergii and Quercus turbinella
Rhus trilobata ‘Autumn Amber’ (right)
Thanks to: Colorado Nursery Research and Education Foundation (CNREF) and Colorado Agricultural Experiment Station (AES) for partial financial support for this project. Partial in-kind donations of plant material are also appreciated form Fort Collins Wholesale Nursery and Bailey Nurseries Inc..