Beardtongue, Penstemon grandiflorus, one of the showiest of all native Penstemons, can reach heights of three feet with stunning pink to purple flowers that bloom for a few weeks in May or June. The bloom time is short, but the plant has beautiful vertical structure and unique foliage, making it a versatile player in the garden or naturalized setting. Beardtongue has distinctive blue-gray or blue-green foliage. The clasping leaves have a succulent appearance. It is noted for its large, tubular, blue-lavender flowers and its hairless, broad-ovate leaves. Flowers bloom in upright, open racemes in late spring. Foliage consists of thick, toothless, opposite, clasping, blue-green leaves, with the basal leaves obovate and the stem leaves rounded to elliptic.
The blooming period occurs from late spring to early summer, lasting about 3 weeks. Each flower remains in bloom for only a short time. The flowers are replaced by ovoid seed capsules that are a little longer than the toothed calyx. Each capsule contains numerous small seeds. The seeds are distributed to a limited extent by the wind when the stems of flowering plants sway back and forth. The root system consists of a stout taproot with coarse secondary roots. This taproot extends deep into the soil.
Habitats include dry sand prairies, dolomite prairies, and gravelly hill prairies. Because of the showy flowers, Beardtongue is more often found in flower gardens, from where it rarely escapes. Fire is supposed to be harmful to the ecological success of this plant because its growing buds remain above ground. In its natural habitat, significant wildfires rarely occur because of the sparse vegetative cover.
Best grown in gritty, dry to medium, well-drained soils in full sun. Avoid moist, poorly-drained clay soils. Plants may be cut back to basal foliage after bloom to improve appearance of the planting. May be grown from seed. Plants will self-seed in optimum growing conditions.