In response to our reader survey, the Denver Gardeners blog is adding a monthly feature on native plants by CSU Extension-Denver Master Gardener Kathy Roth. Kathy is an experienced Master Gardener who has researched, planted and maintained native landscapes and gardens since 1995. She currently grows three native trees in pots on a downtown condo balcony.
By Kathy Roth
CSU Extension-Denver Master Gardener since 2018
Spring officially arrived March 20th…but we can easily remember the piercing winds and bountiful snowfall of just a few weeks ago! Unfortunately, many homeowners experienced tree damage and/or loss due to late Spring (or last year’s early Fall) snowfalls and are now looking to replace those trees. This is the perfect time to consider a native tree choice.
What exactly is a “native tree” you ask? According to the USDA, a Native Plant (or tree) is “A plant that is a part of the balance of nature that has developed over hundreds or thousands of years in a particular region or ecosystem. Only plants found in this country before European settlement are considered to be native to the United States.”
Native plants and trees are important because they are adapted to our climate, soil and environmental conditions. They require less maintenance, watering, fertilization and pruning and are affected by few insect or disease problems. Landscaping with native plants helps maintain biodiversity that is often lost to land development. When non-native plants are introduced, they may threaten our ecosystems as they often out-compete natives. These invaders may cause many birds, mammals and insects to lose their food source, causing Colorado’s wildlife residents to become scarce and threatened.
Some non-native trees have brittle wood that can split and/or have branches that ‘peel’ down the trunk like a banana if wet snow collects in the crotch where limbs attach to the trunk. In Springtime, many non-natives leaf out too early and can be ‘caught out’ by our heavy, wet late Spring snows that collect on leaves and whose weight pulls, breaking branches and limbs. Extreme temperature fluctuations, such as those we experience in the foothills areas, also adversely affect many non-native trees.
A myriad of free online resources on various garden topics are available to the public on the Colorado Extension website. One such resource is Plant Talk. #1710 gives a brief overview of some native tree options. Cheerful evergreens splash our brown winter landscapes with much needed color and their needles are flexible in winter winds, resisting snow damage.
Large evergreen tree suggestions that grow to about 45’ or higher when mature include:
- Our state tree the Colorado Blue Spruce (attractive horizontal branching and high wildlife value to both song & ground birds – even grouse and small browsers)
- The Limber Pine (large ornamental cones)
- Southwestern White Pine (bark has an interesting scaly texture when mature)
- Ponderosa Pine (my favorite due to the bark turning cinnamon color with age and giving off a vanilla fragrance on warm days – plus it tolerates our alkaline soil well)
- Douglas Fir (fast growing with medium to dark green needles and a classic pyramidal shape; provides browse for deer & elk)
- White Fir (conical shaped, drought & heat resistant with soft blue green needles but prefers protection from wind)
If your property is not large enough to accommodate the massive specimens listed above, smaller evergreens whose mature height varies from 10’ – 45’ include:
- Pinyon (compact & bushy)
- Bristlecone Pine (unusual artistic branches have bottlebrush appearance)
- Rocky Mountain Juniper (produces berry-like fruit that is an important food for small mammals and birds)
- Utah Juniper (also produces food for wildlife in the form of large, grayish-blue berry-like fruits)
If you are looking for deciduous trees, please consider:
- Big Tooth Maple (provides orange-red Fall color)
- Gambel or “Scrub” Oak (shrub-like growth whose leaves are red, orange, yellow or brown in fall and its acorns provide excellent wildlife food)
- My personal favorite originates from the Plant Select Program called Hot Wings Tatarian Maple (Acer tataricum GarAnn’). Reasons include unique red samaras (“propellers” or “helicopters”), the leaves’ spectacular Fall color and that this tree thrives in our alkaline soils rather than struggles with iron chlorosis like non-native maples.
CSU also provides Fact Sheets specific to Native Colorado tree choices. Dr. James Klett from CSU wrote “Native Trees for Colorado Landscapes.” This comprehensive Fact Sheet provides a table that groups tree choices by size, whether evergreen or deciduous, their moisture requirements, and brief descriptions or comments about each tree selection.
The Colorado Native Plant Society offers readers a list of local businesses where native trees can be purchased.
The Colorado State Forestry Service also offers bulk purchase of tree seedlings for large property owners. By bulk, I mean bundles of 20-30 trees per species. Inventory may be limited as ordering begins in November. The CSFS Nursery relies on cooperating agencies to promote and sell most of its seedlings to landowners in their respective regions. Seedling cooperators include CSU Extension, conservation districts and CSFS field offices.
Lastly, a visit to Denver Botanic Gardens will enable you to see many native trees and plants growing “in-situ” or in place. The garden’s Native Plant Collection consists of over 700 species belonging to 323 genera. To focus on locating & viewing their Native Trees, simply use their Navigator.
NEXT MONTH’S WILD ABOUT NATIVES: Native Shrubs