21 Trees & Shrubs to Grow in Eastern Colorado

Here are the top 21 trees and shrubs I would recommend growing in eastern Colorado and similar environs. This is the meaty portion of the One Gardener’s Trash is Another Gardener’s Treasurer article. I began planting windbreaks in 1996 and have planted thousands of seedlings and young trees of numerous varieties since then. Maybe half of those, if that, still remain. This is the distillation of digging thousands of holes with a shovel, planting, hauling water in drought years, installing drip irrigation, maintaining drip irrigation, and noting what survives and what doesn’t.

In 1996, you didn’t necessarily need to install drip irrigation with your seedlings, though the conservation district folks recommended it. Most years back then, there was enough rain that the fields would green up and provide grazing for livestock. Now, there are years where the fields have stayed brown from drought, and I wouldn’t plant a tree or shrub without a means of providing supplemental water. Honestly, I’m not certain it still makes sense to keep planting out in the open fields, at all.

For a tough growing situation such as we have here in the shortgrass prairie of semi-arid eastern Colorado, what would I recommend where plants will grow in the open with little tending and supplemental water? It’s not the stately sugar maples, lovely dogwoods, or mountain laurel that thrive in the acidic soil, plentiful rainfall, and forested hills of the eastern states. Here, it’s a very different world. Read on….

Deciduous Trees

Siberian Elm or possibly Chinese Elm would be the only deciduous trees I could suggest without reservation. I’ve tried Burr (or Bur) Oak, Green Ash, Honey Locust, Black Locust, Box Elder, Common Hackberry, Russian Olive, Autumn Olive, numerous types of maple, and the only one I can recommend is Siberian Elm. American Elm may grow in a yard with some wind protection and supplemental water. I’ve also been able to grow some Green Ash and Honey Locust in the yard, where they have some protection from wind and occasionally get supplemental water from drip irrigation. Silver Maple and Norway Maple grow well in the cities, but not out here. Of the maples, only Tatarian Maple (Acer tataricum) has grown well – in my little sheltered front yard area.

Evergreen Trees

For a conifer, hands down pick the Rocky Mountain Juniper and Eastern Red Cedar. The best conifer here, though fairly slow-growing, is the Rocky Mountain Juniper (Juniperus scopulorum), with the Eastern Red Cedar (Juniperus virginiana) a close second. The reason I place Eastern Red Cedar second is that it has more of a tendency than the Rocky Mountain Juniper to develop reduced branching and needle growth on the windward side. Where it doesn’t get the full force of the wind, it grows large and beautiful, spreading out more than the juniper into a broader tree. While the juniper branches are denser, and held closer and more upright, the cedar branches are more horizontal with more evident spacing between the ends of one branch and another.

As far as color, the juniper may have a bit of a slate or blue cast, while the cedar is darker green and may have a red or rusty cast, especially in the winter months. Some of the cedars turn a bit brown in winter, but are still healthy and return to green for the summer. I have juniper and cedar growing in both sandy and high-clay adobe areas where Ponderosa Pine won’t grow. Both juniper and cedar are more tenacious and display higher disease and pest resistance than pines. In the photo below, the two greener trees with more upright branches shown on the left are Rocky Mountain Junipers, and the darker, less dense tree to the right is an Eastern Red Cedar.

Pinon Pine – though some may be found, they don’t always grow well here. I do have one amazing pinon pine that I found recently after years of neglect, still amazingly green and looking great, though still small.

For the most part I wouldn’t bother with Blue Spruce either, unless you can provide shade, wind protection, and extra water for them for a few years while they become established. A neighbor has a large stand of them that was lovely, but they were planted decades ago when there was more rainfall, and have been drying out and dying over the past several years.

Ponderosa Pine and Austrian Pine both have their place. I’ve read that Ponderosa Pine doesn’t like heavy clay soils. The pine and the spruce seem to be more susceptible to disease and pests than the juniper and cedar, and Austrian Pine tends to succumb more readily than Ponderosa. The needles grow longer on a Ponderosa than on Austrian. Between the two, Ponderosa have done better here than the Austrian. Where pines have failed, I’ve filled in with Rocky Mountain Juniper.

Don’t even bother with high-elevation evergreens such as fir, lodgepole pine, bristlecone pine, or most spruce.

Evergreen Shrub

For an evergreen shrub, the Sea Green Juniper can’t be beat. They’re hardy, drought resistant, and can grow fairly large with a broad spread. For a smaller evergreen shrub, you can use a dwarf Pfitzer Juniper, but those are less hardy than the Sea Green variety.

Deciduous Shrubs

For shrubs, the most drought-tolerant and rodent-resistant are the Three-leaved Sumac (Rhus trilobata), also known as skunkbush, among other monikers; and New Mexican Privet (Forestiera neomexicana), which may also be known as Desert Olive, Wild Olive, or New Mexico Privet. Neither grows fast, but they are superb in this environment. The Rhus trilobata grow about 4’ high and wide (larger beside a building), and birds, particularly robins, love their red berries in summer.  I also like the Peking Cotoneaster (Cotoneaster acutifolia). They grow about waist-high here, fairly rounded, with beautiful semi-glossy dark green leaves. A row makes a lovely summertime hedge. They get dark purplish-black berries in the fall, but I don’t know what eats them besides my chickens. I’ve read that plants sold as Cotoneaster acutifolia may actually be Cotoneaster lucidus. I have purchased Cotoneaster acutifolia from the Forest Service, and Cotoneaster lucidus from a nursery, and although they look similar, the lucidus have not grown long enough for me to establish that they and acutifolia are the same.

Siberian Pea Shrub (Caragana arborescens) is touted by the Forest Service, but I’ve had mixed results with them here, and most of those that did grow were short lived. I have also had mixed results with Silver Buffaloberry (Shepherdia argentea) – most have dried out in the summer, though several remain growing well in a semi-protected area with soil enriched from spillover from a chicken yard. In that area, new buffaloberry are spreading voluntarily along the chicken yard fence. Both the caragana and shepherdia do nicely in a yard, but not so well out in the open.

Native American Plum (Prunus Americana) and Nanking Cherry (Prunus tomentosa) can hold their own in a windbreak row and thrive in a yard. Some kind of rodent (voles?) likes to tunnel through the dirt and eat the roots off the Nanking Cherry bushes. Nanking Cherry fruit is small but delicious, and I’ve made a nice Native American Plum/Crabapple jelly. The plums can be yellow or red. Native American Plum may be designated a tree, but here they’re more of a shrub size. They have the benefit of spreading by suckering up from the roots, which is a handy survival trait. I’ve tried Sand Cherry (Prunus besseyi), but all of those disappeared within two years.

Golden Currant (Ribes aureum) is awesome – very hardy, growing year after year even when neglected. These can spread a short distance by suckering up from the roots. If livestock eat them to the ground or they dry up during a drought, they generally grow back by the following year. There are volunteer plants cropping up under evergreens and other trees where their seeds have been spread by birds, presumably passing through in the birds’ droppings. I would put Golden Currant on a must-have list for wildlife food value – birds evidently eat the currants – and for its ability to survive in a tough environment. The currants can be on the tart side, but I eat them, and they could be used to make jelly or a cobbler. I’ve tried alpine and other currants, but none thrive like the Golden Currant.

Lilacs are surprisingly drought tolerant. I even have one whose leaves come in tinged with purple before becoming green.

Both Golden Currant and various lilacs (common, Persian, and the French hybrids) do well in a yard or garden, along with chokecherry (Prunus virginiana) and several varieties of crabapple. Lilacs (Syringa vulgaris) are so successful here that I nearly started a small nursery of unusual and hard-to-find lilac varieties (many having particularly dark or unusual flower color), as well as varieties of crabapples (mostly own-root) for local sale.

A Few More…

I have tried growing American Elder (Sambucus canadensis) and Wild Grape (Vitis riparia). I was curious to see if either of those would run rampant such that the hens and I would become lost in the jungle – somehow I doubted it. I was right. One tenacious elderberry plant that held on for a few years finally kicked the bucket along with the others. The wild grape didn’t make it.

I have one aspen that does well beside the house next to a downspout. Prairie Sky Cottonwood can be fairly successful. At least they can spread by suckering up from the roots, which helps them survive.

In a not-so-tree-friendly environment such as this, there is little problem with weedy spreading of unwanted trees. Rarely, a Siberian Elm is found growing voluntarily in a windbreak row or field. There is virtually no spreading of Eastern Red Cedar or Tatarian Honeysuckle. In general here, if you don’t plant and tend a tree or shrub – at a minimum keeping it mulched or cultivated – it isn’t likely to grow. In friendlier environments, such as Denver, yes, I’ve seen American Elm and varieties of juniper and cedar – along with aspens and who-knows-what-else – sprouting up unbidden in lawns and flower beds. With trees – as with much else – the old adage applies: “One man’s trash is another man’s treasure.”

Paula Reinbold

© February 2, 2023