Gardening Column from the Daily Sun

Whetting the Penstemon Appetite

CINDY MURRAY Master Gardener | Posted: Saturday, March 19, 2011

My neighbor, Judah, one a blustery June afternoon asked me, "Cindy, what're all those tall pink flowers growing in your front yard?"
"Oh yes, they're my Palmer's Penstemons."
"Oh, that's what they're called! Could you spare a few plants?"
I said, "Sure. Come on down. We'll dig up a few."
Penstemons have a way of doing that to a person. Once people see these seemingly delicate beauties, they want to grow some for themselves.
Penstemon is a genus of perennial wildflowers composed of 250 species endemic to North America with the highest concentration growing in the Four Corners area. Arizona boasts over thirty native Penstemon species, many of which grow in the Flagstaff area. The name, Penstemon, comes from the Greek pente meaning five and stemon meaning thread, referring to a filament-like and sterile fifth stamen. Since the sterile stamen is hairy and hangs out of the bilaterally symmetrical tubular flower, Penstemons are sometimes dubbed "beardtongues." Most are hummingbird magnets.
Penstemon blossoms may be delicately beautiful, but the plants can be tough as nails. Jennifer Temkin of Flagstaff Native Plant and Seed says, "Penstemons generally prefer full sun and dry soil. They don't like wet feet." Additionally, they're best left to their own devices-too much fertilizer or mulch will shorten their normal several-year lifespan.
One of the first wildflowers to herald in the summer season is the Rocky Mountain Penstemon (Penstemon strictus). Don't let the name fool you -- it's native to our region and you can't miss it. Sporting deep purple, slender flowers on 2- to 3-foot stalks, it thrives on gravelly roadsides, ponderosa forests, and open meadows. Its dark green foliage stays lush all winter.
Another early bloomer is the imposing Palmer's penstemon (Penstemon palmeri). Its inflorescence consists of a 2- to 7-foot stalk bearing pale pink flowers. The Palmer's blossom consists of a uniquely large, bulbous tube with two small upper lobes and three rounded lower lobes. This provides the perfect landing platform for a prime pollinator, the bumblebee. Judah says her favorite thing about Palmer's is the exquisite fragrance, a rare attribute in the genus.
At the opposite end of the size spectrum are the diminutive pineleaf Penstemon (Penstemon pinifolius) and narrowleaf Penstemon (Penstemon linarioides). Both form compact clumps less than 15 inches tall. Pineleaf is noted for its narrowly tubular crimson flowers and bright green needlelike leaves. Narrowleaf has lavender flowers and tiny linear leaves. They're great specimens for rock and fairy gardens.
Growing throughout ponderosa pine forests and roadsides all over northern Arizona is the beardlip penstemon (Penstemon barbatus). Its tall spikes hold dense clusters of drooping vermilion flowers. Beardlips are more tolerant of shade and moisture than the average penstemon.
My most prized penstemon is the Sunset Crater penstemon (Penstemon clutei). In the wild, it's geographically restricted to the cinder fields of Sunset Crater National Monument. At first glance, you might confuse it with Palmer's, but the stalks are much shorter and the blooms are a deeper pink. Although rare, this penstemon is not difficult to grow. Mine thrive along the edge of the gravelly ditch at the front of my property. As with others of the genus, I deadhead regularly to encourage new flower stalks throughout the summer and into the fall.
Because Penstemons typically take two years to flower, propagation by seed calls for a bit of patience. Temkin says penstemon seeds also require a cold treatment, which is simple: to simulate a winter's exposure to cold, mix sand or perlite with the seeds in a ziplock bag and add enough water to make the mixture moist. Put it in the refrigerator for one to three months. Once the ground has warmed in the spring, stomp the mixture into the soil. Water regularly until the monsoon kicks in. Of course, you can avoid all this by purchasing plants at a nursery, but not all varieties are always available.
The list of penstemon species that thrive in the high country is too long to address here, but hopefully, this introduction will whet your appetite. You may even become one along with me and Judah, a "Penstemaniac."

Cindy Murray, a biologist and substitute elementary teacher, is a Master Gardener. Dana Prom Smith, editor of the gardening column, can be contacted at stpauls@npgcable.com.