There are over 250 species of penstemon with precious few commonly available in American retail garden centers. Although growing in popularity due to their somewhat xeric nature, most are still only available through specialty growers. Commonly called beard tongue in reference to their bell shaped, lipped flowers their native habitats range from Canada to Mexico and through all types of terrain. A number of species are native to the American midwest and thus the characterization of prairie perennials has stuck with me. Most species have narrow, pointed leaves which are larger at the basal clump and smaller on the flowers stems. The need for fast drainage spans the genus–heavy wet soils will shorten their lives considerably.
A struggling clump of Penstemon digitalis ‘Red Husker’ was my introduction to the genus in the early 2000s. I had read about the cultivar being named the 1996 Perennial Plant of the Year and was easily able to find it at my local nursery. The heavy, almost always wet soil of my Georgia garden was not the best fit for its cultural needs and although I got lots of leaves and flowers, the bloom bearing stalks always laid on the ground! And so I wandered away from the penstemon world, my interest being rekindled when the intrinsic nature of my more alkaline, less humid garden canvas seemed to be an environment more friendly to this diverse group.
Penstemon x mexicali ‘Red Rocks’ was the first addition to my current garden. The original colony has waxed and waned over its 7 years, having been progressively shaded out by a large Raywood ash tree. The mexicali hybrids have some of the finer foliage and smaller flowers of the genus but are prolific bloomers.
Many of the penstemon hybrids, commonly called border penstemon or garden penstemon, have large exuberantly marked flowers. Hybrids in this group are tall, quite upright and bushy plants, often 3 feet or more tall and wide.
This clump of Penstemon ‘ Midnight’ was cut to the ground a couple of months ago and is now coming into it own again. The flower stalks exceed 40″ tall and the individual blooms are heavily marked with white.
I don’t know who Bev Jensen was but she must have been one flirty girl to have this gorgeous raspberry penstemon named after her! Wide, heavily marked blooms and ramrod straight stems make her a standout in my garden. Be cautious with fertilizer–penstemons like to live a lean life and excess fertilizer will produce lush growth but minimal blooms.
Another favorite is ‘Apple Blossom’. Mature clumps can reach 3 feet by 3 feet and will provide a show all summer long.
The pink flower sports a clear white throat and they are especially charming just before they open.
This clump of Penstemon ‘Garnet’ has been a standout in my garden since 2010. I regularly cut it to the ground midsummer, encouraging it to bloom well into fall. The flowers are plentiful although a bit smaller than the last two cultivars.
It does dual duty acting as both a support for gladiolus planted behind it and camouflage for the bare base of a climbing rose.
Above is P. x mexicali ‘Carillo Pink’. It is a little more pale lavender than pink and has taken a couple of years to develop into a strong upright clump.
Penstemon heterophyllus ‘Margarita BOP’ above is a current favorite of California native plant aficionados. It is more adaptable to heavy or clay soils than many of the more showy cultivars. Its name comes from Santa Margarita where the Las Pilitas Nursery is located and the acronym BOP for “Back of Porch” where the chance seedling was discovered growing. Yellow tinged buds open to bright blue flowers tinged a rose-purple color that eventually ages to purple. A more relaxed grower making a tidy mound 18″ by 18″, this cultivar has proven to be both heat and drought tolerant.
My most recent addition is Penstemon hartwegii ‘Arabesque Violet’. I understand it is part of a series which includes a red and a pink also–keeping my eye out for those! Although penstemons can be less long lived than many perennials they offer great beauty and diversity as additions, even if temporary, to mixed beds and borders. As a group they fall right in line for me with hardy geraniums, veronicas and salvias–I am always excited to find one I don’t have and I can always find room for a new one!