Horticulture

Flowers for Mountain Communities
by J.R. Feucht 1

Quick Facts...
-Herbaceous perennials are the best colorful flowers for the mountains.
-Add organic matter to light-colored soils to improve the soil and help it hold more heat.
-Use organic mulches to protect plants from drying out. Remove in early spring to help soil warm.
-Newly planted annuals and perennials may need temporary protection with "hot caps."
-Where the growing season is less than 80 days, grow annuals in containers, such as window boxes and tubs.
-Approximately three-fourths of the nation's land above 10,000 feet lies in Colorado. High elevation, together with terrain features that trap cold air, reduces the number of frost-free days.
- The average frost-free period above 5,000 feet elevation is 138 days; above 6,000 feet, 113 days; above 7,000 feet, 98 days; and above 8,000 feet, only 50 days.

Some lower mountain valleys trap cold air and have shorter growing seasons than higher valleys. For instance, Steamboat Springs, at 6,770 feet, has a mere 49 days average frost-free period; Fraser, 8,560 feet elevation, only 16 days; yet, Leadville, with an elevation of more than 10,000 feet has an average of 77 frost-free days.

Despite these seemingly overwhelming limitations, annual and perennial Garden flowers can be grown and often produce more color than those grown at lower elevations.

Perennials for Color
A survey of 66 mountain communities above 6,000 feet elevation showed that herbaceous perennials provide the best source of colorful flowers for mountain communities. These are listed, along with some useful characteristics, in Table 1. Table 2 lists suggested annuals.

Growing Garden Flowers
The greater amount of solar radiation at higher elevations can extend the growing season. Gardens placed in full sun, such as on south and southeast exposures, usually will thrive. A better microclimate will be created for plant growth if the Garden can be screened from strong winds.

Light-colored granitic (decomposed granite) soils, common in many mountainous areas, are less apt to absorb heat. Add organic matter, such as peat, dark mountain topsoil or manure, to improve water retention and heat absorption. On the other hand, darker soils may warm more slowly in spring due to higher moisture content. Soils also may be low in certain essential nutrients. Test the soil after adding organic material. Contact your Colorado State University Extension county office for soil test information.

Use organic mulches to protect perennials from severe drying where snow cover is not likely to remain during the winter. Mulches also can be a disadvantage by delaying spring growth. Remove them in early spring to allow the soil to warm up.

Plant perennials in spring or early summer as soon as the soil can be worked -- never in late summer or fall. Be prepared to provide temporary cover (frost caps) for both annuals and newly planted perennials.

Gradually acclimate annuals and perennials that are established in containers at the greenhouse or in the home. About two weeks before the anticipated planting time, reduce watering and expose the plants to increasingly longer outdoor conditions. If plants are well-rooted in the containers or are potbound, loosen the outside of the root ball before planting.

When transplanting, use a water-soluble starter fertilizer available in Garden stores. This can be mixed in the water used to water-in the plants.

Where the average growing season is less than 80 days, it is usually more practical to grow annuals in tubs or planters that can be moved to protected locations when frost threatens. Frost can temporarily interrupt the normal growing season and destroy tender annuals and perennials. Another alternative is to plant annuals in window boxes. Heat loss from the building reduces the chances of frost damage and the plants can be easily and quickly covered.

Table 1: Garden perennials for mountain communities 6,000 to 10,000 feet elevation.*
Click here for the Garden Perennial Table 1

Table 2: Annuals for mountain communities 6,000 feet to 10,000 feet elevation.*
Click here for the Annuals on Table 2

*Where growing season is less than 80 days, it usually is more practical to grow plants in pots, tubs or other portable containers.

For more information, click on Planttalk ColoradoTM script(s).

1 J.R. Feucht, Colorado State University Extension landscape plants specialist and professor (retired), horticulture. Reviewed by D.E. Whiting, Extension landscape plants specialist, horticulture and landscape architecture. 2/99.

For more information on flowers, go to the CSU Website by clicking on Flowers .




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Page Updated: April 5, 2007
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