Master Gardener: Penstemon can offer season-long color
By Mary Lou Marchand
Special to the Pioneer
Penstemon or beardtongue, are steadily growing in popularity with gardeners. The tubular blossoms remind us of foxgloves but more varieties of penstemon are reliably hardy in our climate. Given the proper conditions, these plants will flourish with little care.
Penstemon like soil that is well drained, almost dry, and are really unhappy being wet, summer or winter. If you have or are developing a planting area that is sunny, has good drainage, you’ll have a fine home for penstemon. They are drought tolerant once established. A thick mulch of pine boughs will help keep the plants dry over winter.
Penstemon are an American native I first noticed while looking for wildflowers. The common name of beardtongue comes from the bearded or tufted stamen that is part of the blossom structure. The 1996 University of Nebraska introduction "Husker Red" brought penstemon to the attention of home gardeners. "Husker Red" has bronzy purple foliage that adds as much color to the border as the tall stalks of white blossoms.
A cross between "Husker Red" and "Prairie Splendor" was introduced in 2008. "Dark Towers" with its deep purple-red foliage bears spikes of lavender to pink flowers in summer. It is also tolerant of heat and humidity and is supposed to be rabbit resistant. Both "Husker Red" and "Dark Towers" fit best in the middle of the border and bloom in July and August.
To get the best out of them, penstemon’s special characteristics should be considered. Those suited only to a rock garden shouldn’t be put in a border where taller plants will crowd or cover them. Taller penstemon handle crowding a little better but still prefer some elbowroom.
If you’re looking for a low growing penstemon for a rock garden or front of border, dwarf hairy beardtongue (P. hirsutus ‘Pygmaeus’) has creeping stems of maroon-tipped leaves and soft lavender flowers with white throats. It blooms from early summer until early fall but at 4 inches in height, it won’t survive competition from taller plants. "Rondo" is frost and wind tolerant and is a good lower growing penstemon.
Other cultivars that do well in our area are "Elfin Pink" and "Prairie Dusk." "Elfin Pink" produces 12-inch spikes of bright pink tubular flowers in June and has glossy evergreen foliage. It, unlike other penstemon, can be deadheaded for rebloom. "Prairie Dusk" has lavender flowers streaked with crimson on 12-inch stalks. "Mesa," with its lavender blue blossoms, reaches 20 inches in height and blooms in late spring.
One of the nicest surprises about penstemon is that many can be grown as annuals. They do need to be started early, approximately 14 weeks before setting out, but that’s about the time many of us are itching to do some indoor gardening. Penstemon may also be propagated by stem cuttings in late summer or early fall.
Penstemon "Rondo Mix" will bloom the first year if started early and is a hardy perennial for our zone. The two-foot stalks are covered in blooms in shades of deep lavender, pinks, royal purples and some blues. The flowers hold up well to wind and rain. "Electric Blue" grows to 18 inches and "Violet Dusk" reaches two feet. These two also bloom the first year from seed. The "Cambridge Mix" that is mostly pinks and reds is another early starting penstemon.
For horticultural information about annuals and other horticultural topics, go to the University of Minnesota Extension website at www. extension.umn.edu/gardeninfo/
Some penstemon tend to be short-lived perennials while others will reseed. Divide penstemon every three to four years. Plants may be cut back after flowering to improve the appearance of the plant.
Master Gardeners will answer your gardening questions via a voice-mail service. Call 444-7916, leaving your phone number, name and the nature of your question. A master gardener will give you a call to speak with you personally.