Most plants in Colorado thrive in our sunshine – 6 or more hours per day: grasses, most trees and flowers. Many plants will tolerate less sunlight, 2-3 hours of direct light, but will not flourish as well as if they had full sun. They will grow more slowly, perhaps be “stunted” and have sparser foliage than full-sun conditions.
Take a good look at the sun that hits the ground around the property. Looking at each area separately to determine if it gets any direct sunlight at any part of the day, especially in spring and summer. Also consider how much moisture or precipitation each area gets.
If an area gets no direct light, that is “deep shade,” as you would find on the north side of a building, or under an evergreen. There are a few plants that will grow in deep shade, and those will do better if they have extra water. With low light and no water, you will often find bare ground.
If light gets to the ground between branches and leaves, that is “filtered shade.” Many full-shade shrubs, like Mahonia – Oregon Grape Holly, and wax flower will do better if they get a bit of this gentle light.
If the area gets some light, that is “part shade.” Trees well suited for part-shade are Gambel oak and junipers.
Because of our intense sunlight, some plants that prefer full sun can survive in Colorado if they get 3-4 hours of direct sunlight, like viburnums, and burning bushes, but will not bloom well or be as bushy as if they had full sun. If they are given more light and water, the same shrubs will be bushier, taller, and bloom better.
In challenging settings, native shrubs and trees will fare better than those from other areas. For example, Gambel oak will grow better in the foothills than boxwood shrubs, tolerating our alkaline soil, desiccating wind and sub-zero temperatures.
Trees that do well in moist shade are serviceberry and redbud. Shrubs for dry shade areas include buckthorn, privet and Japanese barberry; moist shade shrubs include redtwig dogwood, gray dogwood, viburnums and daphne.
For more information, see the following Colorado State University Extenson fact sheet(s).
For more information, see the following Planttalk Colorado™ script(s).