Photo Of The Week by Larry Hurley ~ Beardtongue leading the way into summer…

Penstemon-digitalis by Larry Hurley in Wisconsin — Penstemon digitalis

Here at my sunny Wisconsin garden, the summer season really starts when the Penstemon begins to bloom in early June, about the same time as false indigo and the ever-present Stella Doro daylilies. I have a couple of patches of Penstemon digitalis (aka “Smooth Penstemon”), one of which is behind this pictured clump of Penstemon ‘Dark Towers’ , closer to the street. Although there are many species of Penstemon, most are native to more arid climates and they don’t do well in Maryland. Penstemon digitalis is native to Maryland and found in Wisconsin but apparently not native to Wisconsin. The Prairie Nursery range map has it native in Northern Illinois and the Upper Peninsula of Michigan, so I am thinking that probably had an influence on where the Wisconsin borders were drawn.

Penstemon digitalis has green foliage and white flowers. It spends most of its time as a basal rosette of foliage (evergreen, even in Wisconsin!), and in late spring sends up the flowering shoots. The species is a nice plant, getting to about five feet in flower in my garden, before the weight of the flowers sends a lot of the shoots sprawling. Dale Lindgren, a professor and plant breeder at the University of Nebraska, worked with this and developed ‘Husker Red’, which was named the Perennial Plant of the Year for 1996. (Note: it’s usually written as Husker’s Red, which is incorrect. It refers to the Nebraska school colors, they being the Cornhuskers.) Husker Red was shorter than the species, with foliage that was red for part of the season. So it had some additional garden interest.

Since then additional cultivars have been released, some are hybrids with other Penstemon species. The one in the Photo is Penstemon ‘Dark Towers’, which has the purple-red foliage year round, and the colorful basal rosettes are welcome here in the Blah months of Wisconsin (say, November thru March, and you could make a case for April). It’s a bit shorter, has pink flowers, and doesn’t need staking. Hummingbirds like it as well as the species. Mine gets a foliar fungal leafspot disease, rust, but it seems to not bother it all that much. In Bethesda I had another cultivar, ‘Onyx and Pearls’ which has purple foliage but white flowers and it was in shade part of the day, and still performed well.

So, I recommend you try them. Get a few of the species for the background, and one of the cultivars for more of a centerpiece for early summer. Sun best; good drainage. If you leave the seedheads, you will probably get seedlings from the species. Deer resistant and rabbit resistant. I had a bit of rabbit damage on one plant in late winter, but as a rule, they leave them alone.

Larry Hurley

Larry Hurley worked at Behnke Nurseries from 1984 until the business was composted in 2019, primarily with the perennial department in growing, buying and sales.

Before landing at Behnke’s, he worked as a technician in a tissue culture lab, a houseplant “expert” at a florist shop, and inventory controller at a wholesale nursery in Dallas. With this and that, ten years passed.

When his wife Carolyn accepted a position at Georgetown University, Larry was hired at Behnke’s for the perennial growing department and garden center at Behnke’s Largo location.

In 2021, Larry and Carolyn moved back to Wisconsin to be closer to family and further from traffic. After 37 years in a shaded yard in Maryland, he is happy to have a sunny lot where he can grow all sorts of new perennials, if only he can keep the rabbits at bay. He also enjoys cooking, traveling, and the snowblower.