Posted by Aaron Barton on Mar 4th 2023
A phenomenal early summer problem solver, Penstemon hit their stride just as spring gardens begin to wind down and summer blooms are only just emerging, providing abundant, long-lasting airy sprays of tubular blooms that effortlessly transform garden spaces and usher in the warmer months to come.
Native to eastern North America, including here in Minnesota, Penstemon digitalis (Pen-STEE-mon dij-i-TA-lis), or foxglove beardtongue, is partially named from the Greek “penta” meaning five, and “stemon” meaning stamen, referring to the four fertile and one sterile stamen of each tubular flower in the genus, with their common name beardtongue referring the tuft of small hairs on the sterile stamen.
Belonging to the plantain family, Plantaginaceae, alongside the likes of snapdragon and foxglove, Penstemon provides excellent height and structure in the garden, producing a clump of basal rosettes with dramatic bloom stems holding panicles of tubular blooms high above the foliage from late spring to mid-summer, ranging in size from 24-48” tall and 24-36” wide when blooming. The true species Penstemon digitalis is right at home in the landscape, with an attractive upright habit, rich green foliage, and bright white blooms sure to please local pollinators, especially hummingbirds. Additionally, Penstemon digitalis also serves as the genetic framework for numerous beautiful garden cultivars of foxglove beardtongue.
Many beautiful cultivars are available in addition to the native species, including the 24-36” tall maroon foliage and pink and white blooms of ‘Husker Red,’ compact 12-24” tall, deep purple foliage and lavender blooms of ‘Dakota Burgundy,’ and the mid-sized, deep red foliage and pink blooms of ‘Dark Towers,’ providing a range of appearances to liven up the landscape.
Well-suited for use in pollinator gardens, cottage gardens, mass plantings, mixed borders, or used as cut flowers, Penstemon prefer well-drained, moist soils and will tolerate clay soils and periods of drought, though root rot will occur in consistently wet soils. Foxglove beardtongue are tolerant of salt spray and resistant to deer and rabbit feeding, performing best in full or part sun conditions, though if conditions are too shaded, blooms may require staking.