Horticulture

Native Herbaceous Perennials for Colorado Landscapes

by I. Shonle, L.G. Vickerman and J.E. Klett1

Quick Facts...
A Colorado native perennial is defined as a plant existing in Colorado prior to European settlement.
Native plant gardens create wildlife habitat for a variety of birds, mammals and insects.
Landscaping with native plants makes a significant contribution to biodiversity that otherwise would be lost to development.
Native plant communities in Colorado vary due to differences in exposure, elevation, rainfall, soils and temperature extremes. These plant communities make Colorado visually distinct from other parts of the country.

For a look at the photos and to view this fact sheet, click here Fact Sheet 7.242.
There are many benefits to using Colorado native herbaceous perennials for home and commercial landscapes. They are naturally adapted to Colorado’s climates, soils and environmental conditions. When they are correctly sited, they make ideal plants for a sustainable landscape. Native herbaceous perennials require less external inputs such as watering, fertilizing and other cultural factors when the planting site mimics the plant’s native habitat.

Using Colorado natives in landscapes may attract a variety of wildlife including mammals, birds, butterflies and other beneficial insects. Rapid urbanization in the state is reducing biodiversity (the number of different species found in a given area) as habitat is removed for building and road construction. Landscaping with natives on a large, or small, scale helps maintain biodiversity that otherwise would be lost to development.

The perennials listed in Table 1 were specifically chosen because they require low or moderate amounts of water. Not all perennials listed are available at all nurseries and garden centers, so it may be necessary to contact a number of commercial outlets to find a specific plant. If a perennial is not sold in the trade, asking for it may improve its future availability. Native perennials should not be collected from the wild because this reduces biodiversity, causes a disturbed area that may be invaded by weeds, and may be illegal. Transplanting a wild plant to the garden is rarely successful because of root damage and transplant shock.

Most of the perennials listed in Table 1 are available as container-grown plants. Native perennials often do not have as great a visual impact in the container or immediately after planting as do traditional horticultural species. Over time, however, they will reward the homeowner with their natural beauty.

Where to Grow Native Herbaceous Perennials
Due to Colorado’s varying elevation and topography, native plants are found in a variety of habitats. To maximize survival with minimal external inputs, plants should be selected for your site’s life zone and the plant’s moisture, light and soil requirements. Even if a plant is listed for a particular life zone, the aspect (north, south, east or west facing) of the proposed site should match the moisture requirement. For example, a prairie zinnia, which requires full sun and has a very low moisture requirement, should not be sited with plants requiring higher moisture needs. Similarly, a prairie zinnia should not be planted on the north side of a building, where an abundance of shade and moisture could severely affect its growth and appearance.

Growing native perennials does not exclude using adapted non-native plants. There are many non-native plants that are adapted to Colorado’s climate and can be used in a native landscape as long as moisture, light and soil requirements are similar. Even if a site has a non-native landscape that requires additional inputs (such as an irrigated landscape on the plains), dry land native plants can be used in non-irrigated pockets within the non-native landscape. These native “pocket gardens” can be located in areas such as parkways and next to hardscapes that are difficult to irrigate.

Some communities regulate landscape appearance or the type of plants which may be used. Before initiating a landscape design, check with local authorities, including homeowner’s associations, to discover any regulations that may affect the design.

Life Zones of Colorado

Colorado can be divided into five life zones that are broadly defined by the plant communities that occur at the approximate elevations described below. The Plains life zone, 3,500 to 5,500 feet, is located in eastern Colorado where the majority of Colorado’s population resides. It is dominated by grasslands and streamside cottonwoods. In western Colorado, the Upper Sonoran life zone is located at altitudes below 7,000 feet, and in the San Luis Valley, below 8,000 feet. This zone is characterized by semi-desert shrublands and piñon pine-juniper woodlands at its upper limit.

The Foothills life zone occurs from 5,500 to 8,000 feet and is dominated by dry land shrubs such as Gambel oak and mountain-mahogany, and in southern and western Colorado, piñon-juniper woodlands and sagebrush. The Montane zone consists of ponderosa pine, Douglas-fir, lodgepole pine, and aspen woodlands at elevations of 8,000 to 9,500 feet. Dense forests of subalpine fir and Engelmann spruce dominate the Subalpine zone at 9,500 to 11,500 feet. The Alpine zone above 11,500 feet is a treeless zone made up of grasslands called tundra. Species requiring medium to high moisture occur along watercourses throughout all zones.

Culture and Maintenance

There are three ways to establish a native herbaceous planting: 1) use nursery grown transplants, 2) direct seeding, or 3) using a combination of transplants and seeding. Successful establishment of native transplants requires supplemental moisture from a few months to several years after planting, but this can gradually be reduced. Seedings benefit from supplemental watering until plants are established. Weed control prior to planting seed is critical for success. Nursery grown transplants are best planted in spring or early fall. Seeds can be planted from early to late spring or preferably in late fall.

Native plants can often be successfully grown in unamended soils. Most natives do not require nutrient rich, high organic content soil, and can often become overgrown or short lived in such soils. However, many native plants require well-drained soils. To amend clay soils, add 10 percent compost and 15 percent small aggregate (i.e., pea gravel) by volume to clay/clay loam and incorporate into the root zone. To amend excessively well-drained sandy or rocky soils, add 3 percent compost by volume.

A diverse planting of native herbaceous perennials can support a wide variety of wildlife throughout the season. Leave vegetation standing after the first hard frost to provide over-wintering sites for beneficial insects and birds.

Using native herbaceous perennials offers many benefits in addition to reduced maintenance. The need for fertilizers and pesticides can be greatly reduced or eliminated. Once established, native plantings can help conserve water. Our native plant communities make Colorado visually distinct from other parts of the country and each plant contributes to the biodiversity of the state.

Table 1. Native herbaceous perennials for Colorado landscapes.
For Table 1 in the fact sheet, click here .

One example of a very popular herbaceous perennial shrub,
is the Russian Sage.

If ever a plant was tailor-made for Colorado's climate and growing conditions, Russian sage is that plant. An import from central Asia, Russian sage thrives in our high, dry climate and alkaline soils.

This sturdy plant is characterized by its upright and shrub-like shape, slender stems and finely-cut silvery-gray leaves, which are aromatic and resistant to the browsing of deer.

Russian sage is best planted where it will have room to grow to its mature size of three to five feet tall and three to four feet wide without being crowded. It needs full sun and average soil that drains well.

Russian sage can be a focal feature in a Xeriscape Garden. However it will also tolerate some heavier watering than what is often required in a Xeriscape. The soft, lavender-blue flowers appear in the late summer and remain attractive into the fall. Great companion plants include purple coneflower, sunset hyssop, winecups and black-eyed Susans.

The Russian sage's strong, upright shape provides a presence through the winter months, standing through wind and weather. As spring approaches, the stems should be cut back to the base to encourage new growth.

Plant Select® is a program that seeks and distributes information about the best plants for gardens from the high plains to the intermountain region. It is a cooperative program administered by the Denver Botanic Gardens and Colorado State University Extension, together with landscape and nursery professionals throughout the Rocky Mountain region and beyond.

I. Shonle, Colorado State University Extension agent, Gilpin county; L.G. Vickerman, Extension horticulture agent, El Paso county; and J. Klett, Extension landscape horticulture specialist and professor, department of horticulture and landscape architecture 3/04.


Page Updated: April 5, 2007
Webmaster: Mary Watson


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