Tall and spiky, shrubby and spreading, narrow or broad leaved, sun-loving or shade-craving, penstemons fill a lot of different niches. Known as beardtongues, penstemons are ideally suited for Colorado. Many, in fact, are native to the West.
A hearty, healthy mob, attracting hummingbirds and butterflies, penstemon species include ground-hugging types, small bushy mounds and tall spikes. Leaves may be bluish or bright green, small or large. Most are evergreen. The plants are drought- tolerant and virtually pest-free.
Their reputation for being short-lived is usually because of a zealous gardener’s heavy hand with the hose and soil amendments. Penstemons flourish in loosened, gravelly or clay soils with excellent drainage. Resist the urge to amend the soil, water or fertilize heavily.
Bloom begins in mid- to late spring with the delicate lavender blue of ground-hugging P. procerus. It covers the area with a substantial glossy mat of bright green leaves and dainty flowers.
To attract hordes of acrobatic hummingbirds, plant P. barbatus, or scarlet bugler. The brilliant red flowers rise 2 to 3 feet above the scant foliage.
A native of the plains, P. barbatus flourishes in naturalistic plantings or a dry garden. Exceptional cultivars include “Prairie Dusk,” with rose purple flowers on shorter stems that are 12 to 18 inches tall. Others include “Prairie Fire,” sporting vermillion blossoms on 2-foot tall stems. Lovely “Elfin Pink” displays salmon-pink blooms on 18-inch stems. “Schooley’s Yellow” blooms from late spring to July for a smashing summer display.
P. pinifolius, pine leaf penstemon, is gorgeous in a rock garden. The foliage forms a 12-inch-tall shrubby mound. Flowers are scarlet and cover the mound from June to early September. Cultivars “Mursea Yellow” and “Mango” are especially striking; try pairing them with blue flowers for contrast.
The Rocky Mountain native, P. strictus, famous for lusty spires of indigo and purple, covers the ground with lush evergreen foliage. It tolerates dry or irrigated conditions. Floriferous “Bandera” and “Rondo,” with spikes changing from rose to purple, are excellent choices.
Dryland penstemon, P. grandiflorus, sends up masses of foxglove-like lavender, pink or white blossoms from an evergreen rosette of blue-gray foliage. Even showier is the turquoise foliage mound and tall pink blossoms of P. clutei and P. palmeeri. The foothills native, P. secundiflorus, stands a foot tall, awash in lavender “sidebells.” The plant flourishes in unamended soil and hot sunny locations.
Probably the easiest to grow is P. digitalis “Husker Red.” It adapts readily to traditional flower border conditions, meaning amended soil, ample moisture and crowded plantings. The white blooms float above large maroon leaves on long red stems.
Whether searching for an adorable shrublet, a groundcover or a showy perennial, you’ll find at least a dozen penstemon varieties at local nurseries. Dryland and rock-garden penstemon are best mulched with gravel, promoting reseeding.
Kathi Taylor is a Larimer County Master Gardener.
