A staple in European gardens for decades, penstemons are finally gaining popularity in their native land
In the 19th and early 20th centuries, European plant enthusiasts gathered up penstemon seed from North America, took it home and developed outrageously beautiful hybrids that became mainstays in gardens.
In the U.S., it took a little longer for both breeders and gardeners to catch on.
“It’s hard to say why,” said Maurice Horn, owner of Joy Creek Nursery in Scappoose, Oregon, which has introduced 11 penstemons since 1996. “But almost every garden in England has at least one penstemon.”
American gardeners are finally seeing the light. For more than 25 years, penstemons barely made the cut when Grace Dinsdale put together her plant lists for Blooming Nursery in Cornelius, Oregon. Now at both the wholesale operation and her new garden center and farm market, Blooming Junction, penstemons are difficult to keep in stock.
“They have a lot of fans,” said Dinsdale, who now offers 29 of them. “About seven or eight years ago, people became more aware of them. Now they come in and buy them when they’re not in bloom. It’s almost unfathomable.”
Sharp drainage is key
The winter of 2014–2015 was a good one for penstemons in the Pacific Northwest, where the semi-evergreen perennials aren’t crazy about the winter rains.
“The long and short of it is, this is a celebratory year for penstemons,” Horn said. “It was a mild winter and not too wet, so crown rot wasn’t that much of a problem. That’s not always the case.”
In fact, penstemons are so finicky about soil moisture that excellent drainage is a must. Lucy Hardiman, a garden designer in Portland, said many plantings fail because of that.
“Those who have tried them may not have been successful,” she said. “They take our summers with ease, but not wet winters. The trick is well-drained soil.”
To deal with the issue of drainage, Horn came up with what he calls a “modified rock-garden technique” of adding quarter-10 gravel to the soil before planting and then mulching with the same gravel to wick standing water away from the crowns.
Hardiman employs the same method, sometimes substituting pumice as an amendment, but always mulching with the quarter-10. There’s no need to add fertilizer at planting time, or ever. The plants take their soil lean and mean.
Provide sharp drainage and full sun, and penstemon will bloom from summer — early June this year — to frost. Deadhead and water occasionally to get the best performance from the large-flowered hybrids, most of which are hardy to Zone 7.
“In general, the narrower the foliage, the hardier and more long-lived the plants are for us,” Horn said. Among those are some of the most popular penstemons, such as smoky ‘Blue Midnight’, wine-red ‘Garnet’, the abundant-blooming, rosy-pink ‘Gilchrist’ and true-pink ‘Evelyn’.
“The diminished surface area of the leaves protects the plants from the severity of freezing winds from the Columbia River Gorge,” Horn stated on his website. “The penstemons with broader leaves blacken in this kind of wind. Many times, however, the plants are only damaged and as soon as warmth returns to the Portland area, the remaining stems put out new growth.”
For this reason, and also to leave some texture in the garden, Horn suggests waiting until late winter to prune back penstemon, being sure to cut above active growth.
Native by nature
Counted among the 270 species of penstemon are perennials, shrubs and sub-shrubs. All — from the tiniest rock-garden bun to willowy 5-footers — are indigenous to North America, including Canada and Mexico. Of these, most are native to the western United States, and 50 find their roots in the Northwest. Many of these are alpine plants from the Cascade, Siskiyou and Wallowa mountain ranges.
The plants, which are related to snapdragon, foxglove and cape fuchsia, earned their name from the Greek for five stamens. Of those, one is sterile, often hairy and sometimes falls from the mouth of the flower, inspiring the common moniker of beardtongue.
The blossoms range from long, flared tubes to open trumpets and tend to dangle on one side of the stems in airy racemes. Pollinators, from bees to butterflies to hummingbirds, go crazy for them.
Lorne Blackman, owner of Walla Walla Nursery, speaks highly of species penstemons. But he recognizes that the typical customer gravitates to the large-flowered hybrids.
“When you get down to it,” he said, “the average shopper is going to look at spring-blooming natives out of season and then see the others lush and beautiful. Of course, they’re going to pick those.”
Still, the natives, which are hardier than the hybrids, do well for Blackman. One of the best sellers of the 45 penstemons he offers is P. strictus, an easy-going native of the Rocky Mountains with blue-leaning-toward-purple flowers with no floppiness about them. The 30-by-36-inch evergreen is hardy in Zones 4–9.
His personal favorite is P. pinifolius, which is also held in high esteem by Dinsdale and Hardiman.
“It’s nice because it has needlelike leaves and forms an evergreen mound that you can shear to keep compact,” Blackman said enthusiastically. “It has a long bloom season and seeds itself nicely. All around, it’s a great garden plant.”
The fragrant orange, narrowly tubular flowers of the species are lemon yellow in the selection ‘Mersea Yellow’ and mango in the less-available ‘Mersea Melon’. All of them grow no more than 10 inches tall, bloom June through October and look spectacular with small ornamental grasses like Molina caerulea ‘Moorflamme’ or ‘Variegata’, according to Hardiman.
For Dinsdale, the Northwest native P. davidsonii deserves the newfound attention it’s receiving from customers. The 6-inch-tall, mat-forming alpine named after plant collector George Davidson comes complete with mauve flowers many times the size of its tiny leaves.
“We are starting to see really good sales on this one,” she said. “It was slow to build, but it’s getting some momentum. It’s a really good one in pots and blooms really well. It’s got everything for a garden center plant.”
Hybrids steal the spotlight
What really gets the public going, though, are the hybrids, often referred to as “garden” or “border” penstemons. Though much of the knowledge behind the complex breeding that went into them in Europe more than 100 years ago has been lost, according to Robert Nold in “Penstemons” (Timber Press, 2010), there are five species that are likely parents: P. gentianoides, P. cobaea, P. hartwegii, P. isophyllus and the best-known of the group, P. campanulatus.
“Most of the crosses were done in England,” Horn explained. “They put tremendous effort into getting larger flowers and continuous bloom. But most of those plants met the fate of history. Because of the world wars, the gardening world in Europe had to start over again, not once but twice. There have been some old ones we’ve been able to rediscover, but not many.”
In the 1990s, Horn began his own breeding program at Joy Creek Nursery in Scappoose, Oregon. He started with ‘Purple Tiger’, a robust plant about 30 inches tall and wide with lavender-blue flowers embellished with white and dark purple markings in the throat.
“It’s tough,” he said of his first introduction from 1996. “It tolerates our winters well. We’ve never lost it.”
But Joy Creek is best known for the Kissed series, a group of six seedlings, including the lip-smacking ‘Red Hot Kissed’, selected for large flowers, unusual colors and handkerchief-white throats. The durable, apple-green plants develop into 2–2½-foot clumps.
Around the same time Horn was making selections for ‘Purple Tiger’, Dr. Dale Lindgren at the University of Nebraska was working with P. digitalis crosses and came up with a purple-foliaged form he named ‘Husker Red’, a rock-steady plant that won Perennial Plant of the Year in 1996 and still ranks as one of the trade’s best sellers.
Several years later, Lindgren passed along an improved version to Dan Heims, co-owner of Terra Nova Nurseries, who in 2008 introduced ‘Dark Towers’, a black-leaved beauty with significantly more arresting pink flowers and a striking stature of about 3 feet.
Two series — Taffy and Cha Cha — have also come out of Terra Nova. Heims described the former group, which includes his favorite ‘Grape Taffy’ and the newest ‘Blueberry Taffy’, as having some of the largest penstemon flowers and super-strong, upright spikes up to 20 inches.
As good as they are, it’s the Cha Cha plants that top the charts in Terra Nova penstemon sales, and for good reasons, according to Heims.
“I was looking at ‘Cha Cha Pink’ (the first in the series) in the garden the other day,” he said. “It was huge and loaded with flowers. There must have been 100. That’s what defines the series.”
Plants well with others
In client gardens, Hardiman places penstemons alongside other drought-tolerant, sun-loving perennials like Kniphofia, Agastache, Salvia and sedums. She’s also been known to throw in an ornamental grass or two.
“They’re also stunning with Eryngium,” she said, on a roll. “Another thing I’ve discovered is that they’re great at covering up the ungainly lower legs of asters.”
In her own garden, Hardiman grows the tried-and-true ‘Blue Midnight’ penstemon contrasted against the chartreuse foliage of hardy Geranium ‘Ann Thompson’ with its similar shade of purple-blue flowers. To continue the color-on-color play, she adds Phlox ‘Nicky’ for late-season bloom.
As Blackman looked out his window in Walla Walla, he noted the red-flowering native P. pinifolius planted with Zauschneria, native buckwheat (Eriogonum umbellatum), Nepeta and self-sown lupine. “It’s a super combination,” he said.
Dinsdale summed it up simply, “I think it goes with everything.”