Penstemon, commonly known as Beardtongue, is a diverse and captivating genus of flowering plants that encompasses over 250 species. These plants are native to various regions across North America, from the mountains to the prairies. Penstemons have become popular among gardeners due to their stunning blooms, unique characteristics, and adaptability to various growing conditions. The blossoms are tubular with two-lipped petals that resemble a mouth, hence the common name “Beardtongue.”
Growing and Caring for Penstemon
Most species prefer full sun to light shade, receiving at least 6 hours of direct sunlight per day. Ample sunlight promotes sturdy growth and prolific flowering, enhancing the visual impact of these stunning plants. While some varieties can tolerate partial shade, providing adequate sunlight is essential for vibrant blooms and robust foliage.
Well-draining soil is crucial for the successful cultivation of Penstemons. These plants prefer soil that isn’t waterlogged, as excessive moisture can lead to root rot and other issues. Amending the soil with organic matter, such as compost, helps improve drainage and soil structure, ensuring optimal root health and growth conditions. Penstemons also appreciate slightly alkaline to neutral soil pH levels, typically 6.0 to 7.5. Maintaining proper soil pH helps plants access essential nutrients and minerals, contributing to overall vitality.
Watering practices play a significant role in caring for penstemons. While they are relatively drought-tolerant once established, consistent moisture is essential during their initial growth and flowering stages. Water deeply and thoroughly when the soil’s top inch is dry, but allow the soil to dry out between waterings to prevent waterlogged conditions. Applying a layer of mulch around the base of penstemon plants helps retain soil moisture, suppress weed growth, and maintain a more consistent soil temperature.
Deadheading spent flowers encourages further blooming and helps prevent self-seeding, as some Penstemon species can be prolific seed producers. In late fall or early spring, pruning back the foliage to a few inches above the ground helps rejuvenate the plants and promotes vigorous growth in the following season.
Size and Shape
Penstemons exhibit a wide range of sizes and shapes, with species ranging from low-growing ground covers to tall, upright perennials. The height of Penstemons can vary from a few inches to several feet, depending on the species and cultivar. Some compact varieties, such as Penstemon pinifolius, form mounds of needle-like leaves that reach about 6-12 inches in height. On the other hand, species like Penstemon digitalis can grow up to 3-4 feet tall, creating striking vertical accents in the garden.
Leaves and Flowers
The leaves of Penstemon plants are typically lance-shaped or ovate, and they can vary in size and texture depending on the species. The color of the leaves ranges from vibrant green to gray-green, and some species, like Penstemon gloxinioides, even have bronze or purple-tinged foliage. The foliage of Penstemons adds visual interest to the plant even when it is not in bloom.
One of the most attractive features of Penstemons is their showy and intricate flowers. The color palette of Penstemon flowers is incredibly diverse, encompassing shades of white, pink, purple, blue, red, and even yellow. The throat of the flower often bears unique markings or contrasting colors, adding to its visual appeal. The flowers are borne on tall, slender stalks, creating elegant spires that rise above the foliage. Penstemon is often chosen as a non-toxic substitution for foxglove. The tubular flowers are very attractive to hummingbirds.
Our Selection of Penstemon
At Martin Garden Center, we carry several varieties of Penstemon as grown by our vendors in 4″ containers. The Husker Red variety features burgundy foliage and red flowers, Red Rocks, and the Rock Candy series blooms in pink, red, and blue (more like lilac). At one time, we grew the Pristine series, both Red and Blue and they were beautiful … non-beardtongue-like. However, in 2024, we are not growing any Penstemon due to space limitations. Instead, we will rely on our vendors to keep us supplied. In spring, we will see many varieties available but as we progress into summer, we are less likely to have these beautiful plants available.