Native Penstemons for Low-Water, Pollinator-Friendly Gardens
Grow North America’s native penstemons, also known as beardtongues, to attract hummingbirds and support bees
It would be nice to have a bumper sticker that reads I Brake for Penstemons. Because if there are penstemons growing beside a trail or in a garden, I have to stop. It doesn’t matter if we’re on a tight schedule for a long hike, or if the best angle for a photo takes a bit of precarious maneuvering along a drop-off. Their eye-catching forms are that hard to resist.
“I think penstemons are one of the best native plants we have in North America,” says Dr. Stephen Love, PhD., professor emeritus with the University of Idaho, bulletin editor for the American Penstemon Society and co-author of The Heart of Penstemon Country: A Natural History of Penstemons in the Utah Region. “They're generally a Western species, and most of those are dryland, but there are penstemons for every place.”
Native penstemons offer diverse sizes, shapes and bloom colors for pollinators
“They are an entirely North American genus, from Canada to Guatemala and across the North American continent,” he adds. With approximately 280 species, penstemons earn their standing as the largest genus of flowering plants endemic to this continent. Not surprisingly, the size, structure and flower colors range drastically, depending upon the region.
“Penstemon are known for their clear, strong colors, from the deepest ruby reds to the most stunning amethyst purples. There are some types of species that have subtle colors, such as cream, pale yellow and soft orange,” says Chuck Pavlich, director of new product development at Terra Nova Nurseries, a breeding and propagation nursery in Oregon.
Meanwhile, Love says that in their natural environments in northern parts of the continent, expect to find more blues and purple blooms, while the southern areas boast more pinks, yellows and oranges.
“That's due to pollinators,” he explains. Although there are exceptions, in general hummingbirds use the blossoms in the South, while penstemons attract more insects, including many native bees and wasps, in the northern parts of the country.
“I feel their best advantage is to provide a flower that is both a restaurant and a hotel for bumblebees! We frequently see bumbles asleep in the flower after diving deep for pollen and nectar,” says Pavlich.
Penstemon are also known as beardtongues
Penstemons are nicknamed beardtongues because their tubular flowers typically have tiny hairs lining the protruding lower petal. This feature is actually nature’s way of improving pollination; the insects have to work around these obstacles, which encourage them to delve a bit deeper into the flower.
Just like their flower colors, the structure of penstemon species is variable.
“You have some that are shrubs—they are fully woody— and there are others that bloom and die back. You'd never know they were there,” Love explains.
Heights range from diminutive specimens, such as the three-inch-tall low beardtongue (P. humilis var. brevifolius; USDA Zones 4–8) to giants reaching upward of seven feet tall. One such example is the light pink–flowered Palmer’s penstemon (P. palmeri; Zones 5-9), native to Arizona and New Mexico and one of the few species with fragrant flowers.
Here in Montana, I’m thrilled when I find Alberta beardtongue (P. albertinus; Zones 4–8) blooming on sunny, gravely mountain slopes early in the summer, or masses of lavender-colored Lyall beardtongue (P. lyallii; Zones 4–8) near stream crossings. And I’m always delighted to find them being cultivated in gardens.
The Best Native Penstemons for Gardens
“One of the reputations of penstemons is that they are short-lived,” says Love. “That comes mostly from those derived from European hybrids and bred as bedding plants,” says Love.
He notes there are indeed many penstemon species that may live only for two or three growing seasons, but a good number of these originate in harsh climates where drought is the norm. As a survival mechanism, they produce copious amounts of seed, which remain dormant until the conditions are right for germination and growth.
But drawing from his own decades of experience, he says that “short-lived is a reality for some, but not others.” Some of his plants are 50 years old, and many species have remained in his evaluation plot for 20 years.
Whipple’s penstemon
While working on a book project in the Gallatin Valley of Montana, I visited Crail Gardens in Big Sky. Grow Wild, a local conservation organization, collaborates on this native-plant demonstration garden at the historic Crail Ranch. Drawn to an eye-catching, deep purple penstemon, I inquired about it with Jennifer Mohler, Grow Wild’s executive director, who was directing a watercolor group at their annual Wildflower Festival. She shared that it was Whipple’s penstemon (P. whippleanus; Zones 4–8), native from Montana to Mexico and reputed to tolerate moister conditions and slightly more acidic soils, although Montana is its eastern range edge.
“That species has proven to be more finicky, but I’m determined,” she said, adding that at Crail Gardens she has “been trying to grow every single species of penstemon that could grow in our area.”
Littleflower penstemon
She related that she’s found the diminutive littleflower penstemon (P. procerus; Zones 4–7) to be resilient and prolific even if it grows less than a foot tall.
“It's a workhorse of a wildflower,” she said. “It's jumped out of the garden and started growing in the gravel parking lot.” Because it blooms twice during the area’s brief yet beautiful growing season, it earns extra kudos.
Rocky Mountain penstemon
“The other easy one to grow is Rocky Mountain penstemon (P. strictus; Zones 4–9),” she offered. Reaching up to two feet tall, the bright violet blooms are situated along upright, evergreen stems.
"I just love the abundance and diversity of pollinators they support,” Mohler said of penstemons. “I've found a pollen wasp asleep in the blooms in early morning, too! They are whimsical, each species has unique color and the blooms are fun in flower arrangements.”
Related Article: New & Classic Plants from Intrinsic Perennials
Using penstemon in the landscape
“You could landscape with penstemons,” says Dr. Stephen Love. He shares that he lives in Zone 4, edging on Zone 5, with a growing season of about 110 days.
"I have penstemons in my rock garden that will bloom in May,” he says. “It is the same on the other side of the season. They don’t bloom (continually) all season, but you can stagger varieties.”
Species penstemons may have a short bloom time, but by combining several that flower at different points in the growing season, you can create a long-running penstemon show. And Chuck Pavlich points out that there are some newer cultivars that flower for a longer period.
“Some of the Terra Nova varieties will bloom up to 26 weeks. That’s a really long time as a landscape focus plant,” he says.
The challenge in finding the ideal penstemon is that despite the immense size of the genus, a relative few species are available commercially. Yet with an increasing number of commercially bred cultivars, home growers have more opportunities to explore this phenomenal flower option.
Stunning newer cultivars include the brilliant P. ‘Parade of Parrots‘ (Zones 7–9) and Dakota ‘Burgundy’ (Zones 3–8), whose dark purple-red foliage backs pink flowers.
Related Article: Blackbeard Penstemon Has Lasting Purple Foliage
Tips for Growing Penstemons
Across species, penstemons share many of the same growing requirements. They typically don’t require a lot of fussing. Pavlich shares a few pointers below:
- Most penstemon species come from very gritty, sharply drained soils, so all cultivated penstemon require excellent drainage for a long life.
- Feed them sparingly.
- The best time to plant for most species and cultivars is spring.
- Site them in a sunny position and leave them alone — penstemon do not like to be disturbed.
Penstemon care
One of penstemons’ best qualities is their low water need. “If they wilt in the afternoon sun, give slightly more water until the symptoms of wilting go away,” he notes. Some types also benefit with a little pruning.
- For varieties that are deciduous and die down to the ground, clip them off about two inches above the soil line.
- For semi-evergreen varieties, remove the brown portion down to the green portion, and let it be over the winter.
- When spring returns, they can be cut back farther, or left as-is. One word of caution: As stems age and get woody, they do not produce flowers as frequently as a fresh flush of growth.
