Did you know Denver is characterized as a steppe climate? The term “steppe” is defined as a semi-arid climate with low precipitation (8-14 inches a year), high fluctuations in temperature and a mountain range — in our case the beloved Rockies, which shield us from westerly winds and rain.
What does this mean for those of us who garden?
We face the challenge of choosing plants that can thrive with little water and extreme temperatures. A unique climate presents us with the opportunity for a unique solution — a plant palette suited to our region that allows us to create beautiful, region-specific landscapes.
There are many plants that thrive in a semi-arid climate that also tolerate our summer heat and winter cold. Rather than using plants from the East and West coasts, the South and the Midwest, where soil, temperature and precipitation differ dramatically from ours, we can use plants from other countries that have similar climates.
For example, red hot poker, also known as regal torch lily (Kniphofia caulescens) is a native to South Africa where it lights up acres of terrain with its showy summer flowers. Another garden gem is Diascia integerrima or P009S Coral Canyon ® twinspur. This perennial provides coral pink flowers all summer and throughout fall. Red feathers, or Echium amoenum, is a member of the borage family and is native to Mongolia. This species has upright red blooms on stalks up to 1-foot long from June through August.
Some of the most popular garden perennials have alternative native species that do better in our region.
For example, Echinacea purpurea or purple coneflower, is a popular flower known for its late summer color and its medicinal properties. However, Echinacea angustifolia is the species native to the western United States — it is drought-tolerant and thrives in our native, lean soils. Another example of a native species is Liatris punctata, which is better suited to Colorado’s dry and lean soils than the more commonly found Liatris spicata Kobold.
Cultivated native plants boast improved aesthetics and naturally thrive in our region.
Gaillardia aristata is a short-lived perennial that is native to the western half of the United States. The cultivars of this plant are many and for good reason. Often, blanket flower can become floppy and look unkempt. Cultivated varieties offer bunchier plants with flowers that are bolder, brighter, bigger and longer-lasting.
Another example is rubber rabbitbrush, which is widespread in Colorado. You see it along roadsides, including Interstate 470, Route 85/Santa Fe Drive and in the open plains. The fact that it grows along highways and in open country indicates that it is one tough plant! Rabbitbrush is an excellent pollinator plant and the dwarf cultivar, Ericameria nauseosa ssp. nauseosa baby blue form, is an easy-to-grow, soft textured, manageable and tidy garden plant.
Whatever you plant, remember: Have fun and enjoy! Identifying and utilizing plants that are well-suited to our region makes gardening work much easier.
Luckily, much of this work has been done for us through the Plant Select™ Program (www.plantselect.org). This program, a partnership among Denver Botanic Gardens, Colorado State University and the horticulture industry, identifies and trials plants for our region. Plants that meet the program’s criteria are labeled Plant Select and can be found at your local garden centers— just look for the Plant Select tag!
Whatever you plant, remember that while Colorado has unique gardening challenges, we have unique plant solutions as well!
Annie Barrow is the manager of horticulture outreach programs with the Denver Botanic Gardens. She can be reached at firstname.lastname@example.org.
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