Penstemon digitalis is always the first prairie plant to bloom in my perennial border. Lovely, isn’t it? It’s also well-behaved and completely carefree, so I really, really don’t understand why you don’t grow it. And I’m pretty sure you don’t, because no one I show it to has ever heard of it.
There are three or four native penstemons; most of the others have purple flowers. This species, Penstemon digitalis, also called smooth penstemon or smooth beardtongue, has white flowers, sometimes with purple throats. It is the easiest penstemon to grow and the longest lived. All it needs is full sun and reasonably well-drained soil. Individual plants gradually grow wider and fuller, but the height never exceeds 3 feet. The plants self-seed happily but not aggressively, and they do not spread by rhizomes, so they are easy to keep in check.
Penstemon begins blooming at the very end of May or the beginning of June and keeps going through July. By that time, many prairie plants are in full bloom, so it’s a nice bridge from spring to summer.
There is a naturally occurring form with burgundy leaves. In my garden, some of the seedlings come up green and some red, but all the plants I originally purchased (long ago, from Prairie Nursery in Wisconsin) were green. This next picture shows two plants, one green and one burgundy, growing next to each other. Notice how nice and straight the flower panicles stand. The bright green foliage in front belongs to a Rudbeckia that will be taller than the Penstemon in a month or less, and to the left of the Penstemon you can see junegrass (a native prairie grass, Koeleria macrantha), about to bloom.
To me, when penstemon blooms, that means it’s summer in my garden. Get yourself some summer as well.