Penstemons have been valued for centuries, but it’s only in recent decades that they’ve become more widely planted in Iowa gardens.
Their common name is beardtongues because of the often-hairy stamen that hangs out of each tubular flower. Native Americans used the roots to treat toothaches. The plant first gained horticultural attention in 1748 and by the 19th century British and French horticulturalists were busy creating hundreds of hybrids of the New World wonder plant.
By the 20th century, Americans were also breeding different types. In 1946, the American Penstemon Society was formed, showcasing the hybrids developed, more than 250 species.
Penstemons come in two basic types — tall types that thrive in the heat and drought of the West and shorter types that do well in the cooler, more moist conditions of the Midwest and eastern United States. In fact, foxglove penstemon, Penstemon digitalis, is an Iowa native.
These moisture-loving penstemons demand good drainage but do very well in the richer soils and higher rainfall of the Midwest. Unlike the Western types, they’re hardy up to Zone 3, depending on the type.
A hybridized cultivar of the Iowa native, Penstemon digitalis, or Husker Red, has become a bit of a horticultural star in recent years. It was named the 1996 Perennial Plant of the Year, and has since become a national favorite.
Developed by Dale Lindgren at the University of Nebraska, Husker Red grows up to 30 inches tall, with pretty pale pink blossoms and, unusual for penstemons, beautiful deep purple leaves and stems. They are hardy in Zones 3 to 8.
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Another favorite penstemon for Iowa is Penstemon cobaea, also called purple Ozark beardtongue, it grows up to a regal 30 inches tall with glossy foliage. Lindgren loves the large lavender-purple flowers and their ability to attract bumblebees. They are hardy in Zones 5 to 8.
Sweet Joanne is another excellent cold-tolerant penstemon. Named after Lindgren’s wife, it grows about 2 feet high and wide with striking purple and white streaked flowers.
Red Riding Hood grows 18-inches high with big, white lipped flowers that are especially loved by hummingbirds. It is hardy in Zones 5 to 8.
Penstemon Mexicali Red Rocks is a 1999 Plant Selects winner. With glossy foliage and rose pink flowers, it’s also a vigorous grower. It is hardy in Zones 5 to 9.
With their easy care, long bloom time, striking flowers and ability to attract hummingbirds, penstemons are a must-have for nearly any sunny, well-drained flower garden. Just choose well and you’re likely to find that one type of penstemon isn’t enough. You just might have to try every one you can.
Veronica Lorson Fowler is co-publisher of The Iowa Gardener website at theiowagardener.com.
Tips For Growing Penstemons
• Full sun is a must. Give at least eight hours of unfiltered, direct light and preferably 10 to 12 hours.
• Drainage, drainage, drainage. When possible, plant in raised beds, berms or slopes. Many penstemons are shorter-lived, lasting just a few years and wet soil is a sure way to assure their earliest demise.
• Plant them in masses. Penstemons are rather rangy, airy plants. Just one plant by itself can look a little messy and lost. Plant in groupings of a half dozen or more for best effect.
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• Deadhead regularly. Some penstemons will bloom for many weeks if spent flowers are diligently trimmed.
• Don’t pamper them. Fertilize and water sparingly. They will flop if given too much.
• With their long stems and intricate flowers, penstemons make a fairly good cut flower. They will last three to five days in the vase. Their delicate flowers start to shatter after a few days, but until then, they are spectacular.