Gulf Coast Penstemon, Penstemon tenuis: Spring flowering perennial

Description: Gulf Coast Penstemon, Penstemon tenuis, is also known as Brazos Penstemon, Brazos Beardtongue, Sharpsepal Beardtongue, Gulf Penstemon and Gulf Beardtongue. It is native to southeastern and East Texas. Gulf Coast Penstemon’s foliage is usually up to 12 in. wide and 12 in. tall, but in the spring with flower spikes, it can be as tall as 30 in. Its tapering leaves are usually 3-6 in. long and medium green; in North Texas, it is usually evergreen.

Flowers and Seeds: Gulf Coast Penstemon’s light purple flowers appear in mid to late spring. Although the flowers are small, there are many of them, usually on multiple flower spikes, giving the appearance of a cloud of blooms that last for several weeks. Sometimes Gulf Coast Penstemon flowers again in the fall, although the blooms are more limited. Flowering is followed by attractive, tough 0.5 in. seed capsules containing many small seeds that stay on the plant through the winter, unless cut off.

Planting sites: Partial shade is best for Gulf Coast Penstemon, although it will tolerate full sun. It prefers moist soils and grows well in both moderately acidic and alkaline conditions. It will do well in seasonal poor drainage.

Watering Instructions: Although Gulf Coast Penstemon is quite tolerant of dry conditions, it may be watered during extreme drought.

Comments: Gulf Coast Penstemon is usually grown for its showy, lavender-purple flowers. During blooming, it serves as a nectar source for bees, insects and butterflies and it attracts hummingbirds. Gulf Coast Penstemon’s flowers are fairly long-lasting in bouquets, making it a good plant for a cutting garden. It self-seeds prolifically and after several years, plants can form a thick mat that can serve as ground cover. To avoid having Gulf Coast Penstemon seed out prolifically, cut the flower stalks after blooming. This may also promote a further round of blooming. Companion plants with a similar flowering time include Hinckley Columbine (Aquilegia chrysantha var. hinckleyana) and Golden Groundsel (Packera obovate). Consider planting Gulf Coast Penstemon instead of exotic perennials like Coral Bells (Heuchera spp.), Bugleweed (Ajuga spp.), Dianthus and non-native Coreopsis species.

Written by Dr. Becca Dickstein

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