Evergreen Trees - Evergreen Trees

by R.A. Cox and J.E. Klett1 (4/05)
Quick Facts...

* Most evergreens prefer full sun; some will tolerate partial shade.
* In selecting evergreens, consider space, soil and site conditions, and weather factors.
* Evergreens have different water preferences. Group drought-tolerant types separately from those that require more water.
* All evergreens benefit from mulches. All need sufficient water to become established after transplanting. This varies with species, soil conditions, weather and site conditions.
* Most evergreens benefit from supplemental water during dry, warm or windy periods from November to March.

Narrowleaf evergreen (conifer) trees give a landscape year-round interest, color and texture. Conifer trees are versatile and can be used as specimens, hedges, privacy screens, backdrops for smaller flowering plants, or as a windbreak planted on the north and west to deflect or intercept winter winds. (See fact sheet 7.225, Landscaping for Energy Conservation.)

"Evergreen" refers to trees that normally retain most of their foliage (needles) through the winter. Such trees, however, do not retain all of their needles indefinitely. For example, ponderosa pine drops needles each year that are three to five years old. These older needles are the innermost ones toward the main trunk. Younger needles, further out on the branch, are retained until they are three to five years old. This annual browning and drop of innermost, older needles can cause concern, but it is a natural process. Other evergreens may have needle lifespans of two to 17 years, depending on the species.
Selection

Examine the intended planting space for good soil drainage, adequate sunlight and sufficient space to accommodate the desired evergreen tree at its mature size. Allow for clear access to driveways, sidewalks and entryways. Determine whether the tree's growth will affect any overhead utility lines.
In smaller sites, consider smaller trees or shrubs. (See 7.418, Small Deciduous Trees; 7.414, Evergreen Shrubs; or 7.415, Deciduous Shrubs.) Consider dwarf conifers for limited space areas.
Planting

Before planting, call the utility companies to mark the location of any underground lines to avoid damaging them while digging. Prepare soil before planting by adding organic materials (sphagnum peat moss, aged manure, shredded leaves or compost) in a 1- to 3-inch thick layer over the planting area.

Extend the planting area for several feet in all directions from the actual planting spot. Spade or rototill the organic materials into the soil and mix well 10 to 12 inches deep before planting. If there is sufficient space, use several kinds of evergreens to add variety to the landscape.
Watering and Maintenance

The following list indicates the relative moisture needs of evergreens. Plant species with similar water needs in the same general area -- do not mix trees with widely different water needs.

Evergreens that need less moisture may work well on slopes. All evergreens usable in Colorado prefer well-drained soils. Avoid planting them in swales or poorly-drained, soggy areas. Evergreens that need less moisture may not do well in lawn areas because of the amount of water needed to sustain the lawn. Even for those trees that need more moisture and are compatible with lawn watering, leave the planting area free of sod to allow for good root development. Sod roots compete with tree roots for air, nutrients and water in the soil. An organic mulch is recommended over the entire planting area. (See 7.214, Mulches for Home Grounds.)

Most evergreens growing in Colorado landscapes, whether recently transplanted or well-established, benefit from supplemental water during winter dry spells. Often, such spells are characterized by drying winds or unseasonably warm temperatures, further emphasizing the need for watering. (See 7.211, Fall and Winter Watering, and 7.833, The Science of Planting Trees.)

For gardeners above 6,000 feet, some of the plants listed are not adaptable. Refer to 7.423, Trees and Shrubs for Mountain Areas for specific recommendations. Refer to 7.421, Native Trees for Colorado Landscapes and 7.422, Native Shrubs for Colorado Landscapes for native evergreens.

Contact Information

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Fort Collins, Colorado 80523-4040

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