I recently had the pleasure of taking a road trip across central and southern Colorado and Utah, exploring many of the natural wonders found in those two states. It was an extraordinary trip in which I discovered a variety of geological features, ecosystems found at different elevations, and different impacts of drought. One of the most exciting parts of the trip was seeing native plants thriving in the various landscapes. Some of the standouts were penstemons (Penstemon spp. and cvs., Zones 3–8). They would seemingly appear out of nowhere as bright spots in some of the most desolate areas.
Penstemon diversity in the Mountain West
While there are over 200 species of this perennial, it turns out that 62 of them are native to Colorado. Wow! Penstemons are known for their tube-shaped flowers that attract hummingbirds and butterflies. The common name for these plants is beardtongue, a reference to the tubular flowers that flare open, forming what looks like upper and lower lips.
Diversity within the genus
These hardy perennials come in a variety of colors, including bright blue, red, pink, white, and many shades in between. They also come in a variety of sizes, from low, mat-forming types to larger plants with tall spikes of flowers. The even better news is that they are xeric, tolerate our soils well, and are deer and rabbit resistant.
Here are some native penstemons that I saw on my journey.
P. eatonii, Zones 4–8
Conditions: Full sun to partial shade; well-drained soil
Mature size: 18 to 24 inches tall and 12 to 15 inches wide
Native range: Colorado, Utah, Arizona, New Mexico, Nevada, California
This evergreen penstemon has spikes of bright red flowers, as its common name suggests. It will grow in pretty harsh conditions, as evidenced by the photo above. This species blooms from spring through summer.
P. palmerii, Zones 4–9
Conditions: Full sun; well-drained soil
Mature size: 3 to 4 feet tall and 2 feet wide
Native range: Utah, Idaho, Nevada, California, Arizona, New Mexico
This light pink to white–flowered variety is super hardy and will reseed, as evidenced by the amount we discovered at a state park in southern Utah (photo above). It has a lovely, light fragrance.
Rocky Mountain penstemon
P. strictus, Zones 4–9
Conditions: Full to partial sun; well-drained soil
Mature size: 24 to 30 inches tall and 36 inches wide
Native range: Wyoming, Colorado, Utah, New Mexico, Arizona
Probably the most recognizable native penstemon, Rocky Mountain penstemon’s bright blue flowers put on quite a show in mid to late spring, depending on your zone. This is a long-lived variety that requires minimal care over the years.
—Michelle Provaznik is executive director of the Gardens on Spring Creek in Fort Collins, Colorado.