Which penstemons will thrive in Kansas without special treatment? In particular, which of the vivid blues and reds from the western mountains and deserts will put on a good show out here in the middle of a state that is flatter than an IHOP pancake? Finding out is one of my long-term projects. My extremely scientific procedure is to stick seedlings in the ground at various locations in my yard and see if any survive my haphazard care. After two years, I have some preliminary results. Most of the plants discussed below were started from seed one or two years ago.
Some notes on my location: Although I’ve lived here most of my life, I still can’t tell you what “normal” Kansas weather is. Just as Kansas is neither east nor west nor south nor north, the Kansas climate doesn’t fit neatly into any classification. Although it is supposedly a “humid subtropical climate,” it can with equal inaccuracy be categorized as “cold semi-arid” steppe or “hot summer humid continental.” There is usually an episode or two of sub-zero temperatures during winter, not necessarily with a snow cover, and summers are apt to be very hot, with warm nights. Beyond that, anything can happen. When and how much rain will fall, nobody knows, particularly not the weatherman. Last year was mostly dry; this year has been damp so far, but that can change.
I live near the Arkansas River. Over the centuries the river overflowed its banks and flooded the region many times, depositing soil here. To my non-expert eyes, the dirt in my garden looks like generic black topsoil. It’s deep — I’ve never reached subsoil digging here — and grows luxuriant weeds. The yard is almost perfectly flat. There are no rocks or gravel except for some decorative lava rock one of my predecessors here spread in one small bed.
Given the generally hot summers here, I figure that the species in Dasanthera and Proceri probably won’t do well. Alpines and those adapted to scree slopes or pure sand are likely to be difficult. The rest might be worth a try. Some will grow, some won’t, and the way to find which will survive is to plant them. I’ve focused on species described as “easy,” “adaptable” or “popular,” or which are found in a wide range of habitats.
Unsurprisingly, species native to Kansas do well out here in the middle of nowhere. Penstemons cobaea, digitalis and grandiflorus are all happy and floriferous, no matter where in the yard they are.
In section Elmigera, P. eatonii was one of the first to bloom this spring, and it still has a few blossoms hanging on a month later. The plants are about fifteen inches tall, and the flowers are vivid red. P. barbatus var. coccineus is just starting to bloom. These are vigorous plants, over two feet tall, and they should reach three feet, maybe four. P. barbatus “Twizzle Blue” bloomed the first year from seed. It’s shorter and shrubbier than the other P. barbatus, and the flowers are more densely clustered. The color varies; one is royal blue while the others have purplish-red tubes. (I suspect there are several other species in addition to P. barbatus in the “Twizzle Blue” ancestry.)
In section Glabri, P. mensarum was another early bloomer. In my garden, the flowers were an excellent rich blue, though the exact shade varied with the time of day and the weather — in general, the more sun, the bluer the flower. The plants were about 18 inches tall. I gave some seedlings to a friend up the street, much of whose yard is tree-shaded part of the day. They did very well for her, but the flowers in her garden were a lighter blue. P. strictus started blooming just as P. mensarum finished. These are about two feet tall and may reach three feet. The flowers range from lavender blue to near true blue. The color is best on sunny afternoons on plants in full sun in dry weather.
In section Saccanthera, P. azureus apparently doesn’t like Kansas summers. The seedling in the most exposed garden in the back yard was gone by midsummer last year. Those in the more protected garden south of the house are blooming now. The flowers are indeed large and blue, but the plants are floppy and don’t display the blooms well. (I had to hold the stem up to get the picture above.) Perhaps when the plants get larger they will look better. P. heterophyllus “Electric Blue” survived its first winter and put on a splendid show a year ago. Then it died back, and died back, and died back some more, and it was gone.
Others: P. pinifolius “Compactum” is blooming furiously right now, covered with small orange-red flowers. It seems quite happy in the south garden, and I am trying cuttings in other parts of the yard, hoping that the neighborhood feral cats don’t dig them up again. P. x “Blue Lips,” a hybrid of P. crandallii and P. linarioides v. coloradense, was another early bloomer, and it is still going strong. Out of bloom it looks like a creeping conifer, an inch or two tall and a foot across, with leaves like a yew. P. whippleanus grew strongly for several months last year, then went into shock in July and August, even though I had put the seedlings in the coolest and shadiest parts of the yard and given them extra water. The surviving plants look good right now, but summer is coming. I gave some seedlings to my friend up the street with the tree-shaded yard. They’re doing quite well for her and look like they will bloom later this summer.
On the basis of my experiences thus far, I can recommend Penstemon cobaea, P. digitalis, P. grandiflorus, P. eatonii, probably most forms of P. barbatus, P. mensarum, P. strictus, P. pinifolius and P. “Blue Lips” for Kansas. If a plant can survive in Kansas, it likely will grow almost anywhere. I started a large number of other species this spring, and with luck I’ll have an update next year.
I bought the seeds for most of these from Alplains, Diane’s Flower Seeds and Prairie Moon Nursery. I also purchased a few plants from High Country Gardens.