Colorado is a beautiful state replete with unparalleled alpine allure. But there is more to the state than its surreal and captivating mountain landscapes.
According to the Colorado State University Extension, there are five distinct life zones in CO that are defined by the specific plant life that grows there, and the approximate elevation where they can be found.
The majority of plant life resides in the Plains Life Zone in Eastern Colorado at 3,500 to 5,500 feet. The Upper Sonoran Life Zone occurs between 7,000 and 8,000 ft and is dominated by semi-desert shrubland and Piñon Pine and Juniper.
The Foothills Life Zone occurs from 5,500 to 8,000 feet and features dryland shrubs. The Montane Life Zone occurs at elevations of 8,000 to 9,500 ft, the Subalpine Zone is at 9,500 to 11,500 and finally, the Alpine Zone occupies areas above 11,500 ft and is a treeless expanse known as a tundra.
Let’s look at some Colorado natives to plant today or admire in the wild.
21 Colorado Native Trees to Grow
1. Plains Cottonwood (Populus deltoides)
The Plains Cottonwood is a large native tree that forms a large trunk. The crown is open and spreading and features drooping thick branches. The bark is smooth when young and is yellow-green to light gray, becoming thick and deeply furrowed as it ages. The twigs are stout, brown, and slightly angled.
The leaves of the Plains Cottonwood are triangular and are 3-7 inches long, 3-5 inches wide, and are simple, with long pointed tips and heart-shaped bases with coarse teeth on the margins.
They’re shiny green on the upper side and pale green below. Plains Cottonwood are dioecious, with male and female flowers appearing on different trees. The flowers appear before the leaves and are wind-pollinated.
The Plains Cottonwood in its native range is mostly found in bottomlands and will tolerate almost any soil type provided it’s well-drained. They require full sun and are intolerant of shade. The root system is deep and wide so avoid planting near wells etc.
Other Common Names: Eastern Cottonwood, Black Poplar, Carolina Poplar, Necklace Poplar
Growing Zones: 3-9
Average Size at Maturity: 50-80 ft tall and 35-60 ft wide
Flowering Season: March to April
2. Colorado Blue Spruce (Picea pungens)
The Colorado Blue Spruce is the state tree of Colorado and does well in metropolitan areas. It can be identified by its broad, dense, pyramidal shape and branches that grow horizontally from the ground. The needles are green-blue/silver-blue with an extremely sharp point and a faint white line.
Colorado Blue Spruce needs more moisture than some other CO natives but will tolerate drought and strong winds once established. The Colorado Blue Spruce will grow in a variety of soil types, including acidic, loamy, sandy, and clay well-drained soils.
Other Common Names: Green Spruce, White Spruce, Colorado Spruce
Growing Zones: 1-7
Average Size at Maturity: 30-60 ft tall and 15-25 ft wide
Flowering Season: June
3. Engelmann Spruce (Picea engelmannii)
The Engelmann Spruce and Subalpine Fir (Abies lasiocarpa) form one of the most common forest associations in the Rocky Mountains.
This type of fir has a narrowly conical crown and a gray to reddish-brown bark that is thin and scaly and peels off easily. The thinness of the bark means that the tree often perishes if exposed to fire.
The leaves of the Engelmann Spruce are needle-like whilst the seed cones are long and slender, and cylindrical, with thin and flexible scales. They are reddish to dark purple and mature to pale brown 4-7 months after pollination.
At the timberline, the Engelmann spruce will grow as krummholz but are often seen as straight trees with a spire-like crown at lower elevations. They can be found in areas with long cold winters and short cool summers.
The Engelmann prefers deep rich soil and adequate moisture. In drier areas, Engelmann Spruce can be seen growing with LodgepolePines.
Other Common Names: Silver Spruce, White Spruce, Mountain Spruce
Growing Zones: 3-8
Average Size at Maturity: 80-130 ft tall and 10-15 ft wide
Flowering Season: April-May
4. Gambel Oak (Quercus gambelii)
The Gambel Oak is the only Oak native to CO, and is the most common Oak seen in the Rocky Mountains as well as Grand Canyon National Park, according to Plant Database.
The Gambel Oak is a small tree with a rounded crown or a small clump shrub that sometimes forms thickets. The foliage is deciduous, bright green above and paler on the underside, and are deeply lobed.
The foliage is browsed by deer and occasionally livestock, squirrels, hogs, wild turkeys and other domestic animals eat the semi-sweet acorns.
The Gambel Oak can be found on dry hills, slopes, and canyons at lower elevations and foothills, in rocky-based, calcareous, sandy, sandy-loams, medium loams, and clay-loams.
Other Common Names: Scrub Oak, Rocky Mountain White Oak, Utah White Oak
Growing Zones: 4-8
Average Size at Maturity: 20-30 ft tall and 10-15 ft wide
Flowering Season: March-April
5. Wasatch Maple (Acer grandidentatum)
The Wasatch Maple gets its name from the Wasatch Mountains in the fat southwest of Colorado where it grows in thickets or groves in moist mountain canyons.
It’s a tree of various shapes and sizes and is adapted to different soil types and moisture levels throughout CO. It’s a slow-growing tree, even with supplemental irrigation which, alongside its tendency for transplant shock could be why it isn’t planted more frequently.
The leaves are deeply lobed and are bright green in the summer, changing to shades of yellow, orange, and red in the fall. The bark is smooth and gray. The Wasatch Maple is a good choice for water-wise gardens and works as a small shade tree.
Other Common Names: Bigtooth Maple, Western Sugar Maple, Canyon Maple
Growing Zones: 3-8
Average Size at Maturity: 20-30 ft tall and 20-30 ft wide
Flowering Season: Spring
6. Thinleaf Alder (Alnus tenuifolia)
The Thinleaf Alder is a broadleaf, deciduous tree or multi-stemmed shrub with a rounded form. The bark is thin, smooth, and green-gray. The leaves are oblong/ovate, simple and broadly elliptic, dull green on both sides with a doubly dentate margin.
The Thinleaf Alder is the most common Alder of the Rocky Mountains, Sierra Nevada, and the east side of the Cascades.
It tends to grow near water so its presence is often seen as a sign that streams or springs are nearby. Whilst they are often found near swamps, streams, and ponds, they can also be found well up into the mountains.
Other Common Names: Mountain Alder
Growing Zones: 5-7
Average Size at Maturity: 12-36 ft tall and 15-20 ft wide
Flowering Season: March
7. Rocky Mountain Juniper (Juniperus scopulorum)
The Rocky Mountain Juniper is a needled evergreen tree from the Cypress family that features a dark brown exfoliating bark. It occurs in the foothills and montane zones on dry rocky slopes and mesas. It has a variable growing habit, ranging from upright to columnar, and is almost always single-stemmed.
The branches are spreading to ascending. Leaves are light to dark green and the cones are a waxy shade of blue that attracts many different species of local birds.
The Rocky Mountain Juniper will adapt to many different dry soil types but won’t tolerate the humidity of high nighttime temperatures.
Other Common Names: Mountain Red Cedar, Weeping Juniper, Rocky Mountain Red Cedar
Growing Zones: 3-9
Average Size at Maturity: 30-40 ft tall and 3-15 ft wide
Flowering Season: April to May
8. Peachleaf Willow (Salix amygdaloides)
The Peachleaf Willow is a fast-growing deciduous small to medium tree with weeping branches. It tends to grow in wet areas near a water source such as lakes or streams and is a valuable tree in controlling erosion.
The larger branches are ascending, whilst the smaller ones often droop. The bark is gray and smooth to the touch.
The Peachleaf Willow tree is dioecious with male and female trees producing catkins on separate trees. They attract bees, insects, and other beneficial wildlife. Grows best in full sun to partial shade.
Other Common Names: Narrowleaf Willow, Saltcedar, Almond Leaf Willow, Almond Willow
Growing Zones: 4-8
Average Size at Maturity: 35-50 ft tall and 25-35 ft wide
Flowering Season: April to June
9. Rocky Mountain Birch (Betula occidentalis)
The Rocky Mountain Birch is commonly found growing in riparian woodlands in clumps or thickets around rivers, streams, or other watercourses. It’s often seen as a multi-stemmed shrub but can sometimes be spotted as a single-trunked tree with a broad, irregular open crown.
The bark is red/brown, shiny, and non-shredding and is marked with white horizontal lines. The leaves are broad, ovate, alternate, and deciduous, with rounded bases and pointed marginal teeth. They are dark greenish/yellow and shiny above and paler and gland-dotted on the underside.
In the spring, male and female catkins appear on the same plant, with fruiting cones appearing in late summer. The Rocky Mountain Birch provides food and habitat for beavers.
Other Common Names: Water Birch
Growing Zones: 4-6
Average Size at Maturity: 25-33 ft tall and 20-25 ft wide
Flowering Season: Spring
10. Cork Bark Fir (Abies lasiocarpa arizonica)
The Cork bark Fir is native to the montane and subalpine zones of CO. It has a narrow and pyramidal habit and a thick and cork-like bark that is white gray and deeply furrowed.
It’s commonly seen growing at 7,700 to 11,000 feet above sea level, alongside Picea engelmannii. It also has the potential to be planted at lower elevations.
The crown of the cork bark fir is often conical and tall on younger trees and becomes irregular on older ones. The needles are deep and dense blue-gray and are very glaucous. The Cork Bark Fir will grow best in moist, well-drained clay, sand, or loam soils.
Other Common Names: Subalpine Fir, Alpine Fir, Balsam Fir, White Fir, Rocky Mountain Fir, White Balsam
Growing Zones: 4a-8b
Average Size at Maturity: 40-66 ft tall and 12-18 ft wide
Flowering Season: April-June
11. Quaking Aspen (Populus Tremuloides) – Flowering Tree
Aspens are native to most of North America and are beautiful year-round. They work well planted as a living fence and are a beloved native tree of CO and beyond.
The leaves of the Quaking Aspen are heart-shaped, and dance and sing in the wind, giving it its common name. When the leaves disappear for the winter, you can enjoy the beautiful cream color of the bark.
Quaking Aspens are slim trees, making them perfect for narrow spaces on the north sides of homes as they are hardy down to the coldest mountain zones. They can be grown in partial shade but will look their best when planted in full sun.
These particular aspen trees need more water than some other Colorado native trees and will need regular pruning if you want to keep them in a small space.
They can be found growing in many soil types, especially on well-drained rocky and gravelly slopes.
Other Common Names: Trembling Aspen, Golden Aspen, Mountain Aspen, Popple, Poplar
Growing Zones: 2-8
Average Size at Maturity: 20-50 ft tall and 10-30 ft wide
Flowering Season: Spring
12. Douglas Fir (Pseudotsuga menziesii)
Douglas Firs can be found in the foothills and montane zones of CO. It’s an evergreen coniferous tree with a conical dense crown on young trees that becomes flat and broad with age.
The upper branches are ascending whilst the lower ones are drooping. The needles are flattened and radially arranged and are bright green/yellow and grooved above.
The cones are light-brown woody or semi-woody and have three-pronged bracts and mature in one season.
They can be found on the Pacific coast from British Columbia down to central California, and in the Rocky Mountains down to Arizona and Texas. Douglas Firs are the most important timber species in the United States.
Douglas Firs prefer full sun in slightly acidic to neutral, well-drained moist soils. Occasionally, trees in the wild can be spotted with a non-conventional form.
Other Common Names: Douglas-Fir, Douglas Tree, Oregon Pine
Growing Zones: 5-6
Average Size at Maturity: 40-80 ft tall and 10-20 ft wide
Flowering Season: March to May
13. Southwestern White Pine (Pinus strobiformis)
The Southwestern White Pine is a small tree with an attractive rough bark that is ash-gray in youth, maturing to a darker gray. The Southwestern White Pine has a columnar shape, soft green/blue needles, and long tube-like cones.
The Southwestern White Pine has become a favored pine tree to plant in its range due to its beauty and effectiveness as a windbreak.
It also serves as a valuable habitat for wildlife in areas seeing increasing development. Once established, they need only moderate amounts of water and are slow-growing.
Other Common Names: Mexican White Pine, Chihuahua White Pine
Growing Zones: 5-9
Average Size at Maturity: 50-80 ft tall and 20-40 ft wide
Flowering Season: April
14. Chokecherry (Prunus virginiana) – Flowering Tree
The Chokecherry is a large shrub or small understory flowering and fruiting tree native to Colorado at elevations between 5,000 to 10,000, interspersed with Scrub Oak, Ponderosa Pine, Juniper, Piñon Pine, Cottonwoods, and Aspens.
White flowers appear in abundance and are followed by red fruits that ripen to dark purple from August to September. As the name suggests, eaten raw they are rather unpalatable but they can be made into tasty preserves.
Chokecherries will grow in moist to dry soils in full sun to shade in limestone based, sandy, sandy loam, medium loams, or clay loams.
In their native habitat, they can be found near streams, on prairie hillsides, and rocky bluffs.
Other Common Names: Common Choke Cherry, Choke Cherry
Growing Zones: 2-7
Average Size at Maturity: 20-30 ft tall and 10-20 ft wide
Flowering Season: April to July
15. Boxelder (Acer negundo)
The Boxelder is the only large maple found on the plains and eastern foothills of the Southern Rockies and can usually be found growing near streams.
It can also be found growing near canyons, valleys, and in the lower parts of the Colorado and Rio Grande river valleys. Typically, Boxelder is found at elevations between 4,500 and 7,500 ft.
Boxelder is a fast growing tree and is tolerant of drought, heat, and cold, and for this reason, is often planted as a shade tree in rural areas. Magpies favor Boxelders to nest, so anyone wishing to attract any to their yards can consider planting one. Squirrels and chipmunks eat the seeds.
The leaves are compound with 3-5 leaflets (rarely 7) 4-10 inches long, 1 ½ to 2 ½ inches wide and are bright green with large green teeth.
Other Common Names: Ashleaf Maple
Growing Zones: 2-10
Average Size at Maturity: 35-80 ft tall and 30-50 ft wide
Flowering Season: Fall
16. White Fir (Abies concolor)
The White Fir is a large conical evergreen with soft bluish-green needles. In spring, the new growth lightens up the tree when the new foliage emerges bright blue. If you’re looking for a change from the commonly planted Colorado Spruce, then consider the White Fir, which is a softer-looking tree.
The White Fir will grow in a wide variety of conditions but does best when given some protection. However, planting in heavy clay soils will result in a slower growth rate.
Other Common Names: Concolor Fir, Colorado Fir
Growing Zones: 4-7
Average Size at Maturity: 30-50 ft tall and 15-25 ft tall
Flowering Season: N/A
17. Balsam Poplar (Populus balsamifera)
The Balsam Poplar has broad, heart-shaped leaves similar to the Narrowleaf Cottonwood. The leaves are shiny with resin studded undersides. The buds of this poplar tree are sticky and smell of balsam.
The male trees flower in long dangling catkins before the leaves emerge. Females disperse fluffy seeds into the surrounding areas in late spring.
The Balsam Poplar prefers full sun and moist rich soils and is intolerant of shade.
Other Common Names: Bam, Bamtree, Eastern Balsam, Hackmatack, Tacamahac Poplar, Tacamahaca
Growing Zones: 2-7
Average Size at Maturity: 36-72 ft tall and 25-40 ft wide
Flowering Season: April/May
18. Rocky Mountain Maple (Acer glabrum) – Flowering Tree
The Rocky Mountain Maple is a deciduous broadleaf small tree with an upright habit. The leaves are opposite, simple with 3-5 lobes occasionally divided into 3 leaflets (in moist areas) and are coarsely double-toothed, blue below and green on the upper side. Plant in full sun or partial shade.
The Rocky Mountain Maple tree produces yellow/green flowers that are 5mm across with 5 petals. Fall sees the beautiful shades of yellow.
Other Common Names: Rock Maple, Douglas Maple, Dwarf Maple
Growing Zones: 3-8
Average Size at Maturity: 20-30 ft tall and 20-30 ft wide
Flowering Season: April-June
19. Piñon Pine (Pinus edulis)
The Piñon Pine is a small-sized pine with yellow/green needles about 2 inches long that remain on the tree for about 8-9 years.
It’s an extremely water-efficient tree that thrives on 15 inches or less of water annually. The cones of the Piñon Pine are small and brown and resemble roses. Inside these cones are edible pinenuts.
The Piñon Pine is a slow grower, which eventually develops a crown as wide as it is tall. It’s one of the most prominent pines in the Great Basin Region.
They grow in dry soil in full sun and require little to no maintenance. The Piñon Pine can usually be found growing at elevations between 7,500 feet.
Other Common Names: Pinyon Pine, Pinyon,Two Needle Pinyon Pine, Colorado Pinyon
Growing Zones: 5-8
Average Size at Maturity: 10-30 ft tall and 10-30 ft wide
Flowering Season: Spring
20. Lodgepole Pine (Pinus contorta)
Lodgepole Pines can be found at elevations between 6,000 and 11,000 ft in well-drained soil. They are often found growing in pure stands, near the ocean shore, in dry mountain forests up to the subalpine zone.
The bark is thin, light brown, and features many scales. The needles are evergreen and dark green to yellow, 1-3 inches long, and sharply pointed with two needles per bundle.
The fruit of the Lodgepole Pine is brown shiny serotinous cones (meaning they need the extreme heat of a fire to open) They are 2 inches long with raised and rounded scales.
Other Common Names: Shore Pine, Twisted Pine, Contorta Pine
Growing Zones: 6-8
Average Size at Maturity: 40-50 ft tall and 20-35 ft wide
Flowering Season: April-May
21. Bristle Cone Pine (Pinus aristata)
The Bristlecone Pines can be found on cold, exposed, rocky dry slopes on mountain ridges up to the tree line. The needles are evergreen with dark green with white lines across, and generally 5 per bundle.
The fruit are cylindrical, 2-3 inches long with dark purple, brown cones with 4-sided cone scales with curved points.
The bark of Bristlecone Pine is smooth and gray on younger trees, and red, and brown with scaly ridges on mature specimens. Bristlecone Pines can be found in CO at elevations between 9,200 to 11,800 feet.
Other Common Names: Rocky Mountain Bristlecone Pine, Colorado Bristlecone Pine, Foxtail Pine, Hickory Pine
Growing Zones: 3-10
Average Size at Maturity: 8-20 ft tall and 10-15 ft wide
Flowering Season: Late winter/early spring
Colorful Colorado
The state of Colorado is home to a diversity of landscapes which in turn support a range of flora and fauna. What grows and what is suitable to plant in this mountainous state is often dictated by your elevation above sea level.
Due to the climate and planting zones of CO, it is an outdoor lovers’ paradise, with many different species of trees that can be either admired in the wild or planted in your yard. Planting natives has the benefit that they are already adapted to the local environment, and will require little maintenance.
They also provide help to the local ecosystem so are a valuable way you can give back to the community.
