Penstemon: How to Grow and Care with Success

What is Special About Penstemon?

Penstemon, with its vibrant blossoms and adaptive resilience, holds a special place in the hearts of gardeners, landscapers, and environmentalists alike. Here’s what makes it stand out:

Diverse Bloom Colors and Forms: Penstemon flowers exhibit a remarkable range of colors, shapes, and sizes. From the bright reds of Penstemon pinifolius (Pine-needle Beardtongue) to the striking blues of Penstemon heterophyllus (Foothill Penstemon), and the delicate pinks of Penstemon palmeri (Scented Beardtongue), there’s a Penstemon to complement every garden palette. The blooms, often tubular and two-lipped, are uniquely structured to accommodate their pollinators, mainly hummingbirds and bees.

Adaptability: Penstemons are exceptionally adaptable, capable of thriving in various climates and soil types, though they prefer well-drained soils and areas of full to partial sun. This adaptability makes them suitable for diverse landscapes, from rocky slopes and woodland gardens to prairie settings and urban garden plots.

Pollinator Attraction: The flowers are a magnet for pollinators. Their nectar-rich blossoms are particularly enticing to hummingbirds, various species of bees, and butterflies, making Penstemon a vital plant in pollinator-friendly gardens and crucial for supporting local ecosystems.

Extended Blooming Season: Many Penstemon species and cultivars have a long flowering period, often from late spring through late summer, and sometimes into fall, providing sustained color and food for pollinators when other blooms may be scarce.

Ease of Care: Generally low-maintenance, Penstemons require minimal care once established, being relatively drought-tolerant and often needing only occasional pruning to maintain shape and encourage new growth and blooming.

Native Status: Numerous Penstemon species are native to North America, making them an excellent choice for native plant gardens and naturalized landscapes. Their use supports local biodiversity and ecosystem resilience.

Versatility in Landscape Design: Penstemons fit into various garden designs, from formal perennial borders and cottage gardens to rock gardens and naturalized wildflower meadows. Their vertical growth habit adds height and structure within garden beds or as standalone specimens.

Heritage and Cultivation: With a rich history of cultivation, Penstemons have been beloved by novice gardeners and horticulturists alike. The ongoing development has led to numerous hybrids and cultivars, each with its unique characteristics and charm.

When to Plant Penstemon

The optimal time to plant penstemon varies depending on the climate of your area, but generally, the best times are in the spring or early fall.

Spring planting allows the plants to establish themselves during the warm summer months, while early fall planting takes advantage of cooler temperatures and typically more abundant moisture.

Where to Plant Penstemon

Light: Most Penstemon species thrive in a location that receives full sun for at least 6 to 8 hours daily. They need ample sunlight to bloom generously and maintain strong stems. However, in areas with very hot, intense sun, partial shade in the afternoon can help prevent scorching and provide relief, especially for species native to cooler climates.

Soil: Penstemons prefer well-drained soil. They’re particularly sensitive to soggy soil conditions, which can lead to root rot, a common issue with this genus. While some species prefer rich, fertile soil, many are adapted to poor, sandy, or rocky soils, especially those native to drought-prone areas. Soil amendments such as peat moss and manure should be avoided, especially in dry climates.

Spacing: Proper spacing is important to ensure adequate air circulation around the plants, which helps prevent fungal diseases. The distance should be based on the mature size of the specific species or cultivar, which can vary widely.

Context within the Garden: Penstemons are versatile and can be integrated into various garden designs. They’re excellent in perennial borders, rock gardens, wildflower meadows, or xeriscapes (landscapes that minimize or eliminate the need for irrigation). They can be used as specimen plants, in mass plantings for a dramatic effect, or interplanted with other perennials that have similar growing requirements.

How to Plant Penstemon

• Choose a location with well-draining soil. Penstemon does not do well in soil that retains water for long periods.
• Prepare the soil by loosening it to a depth of 12 to 15 inches (30-37 cm) and mix in a 2- to 4-inch layer of compost.
• Dig a hole twice the diameter of the plant’s container.
• Remove the plant from its nursery pot, carefully keeping the root ball intact. Set it in the hole so the top of the root ball is level with the soil surface. Fill in around the plant with soil and press firmly.
• Water thoroughly after planting. Mulch to conserve moisture, regulate soil temperature, and reduce weeds, but keep mulch a few inches away from the plant stems to avoid rot.
• Water the plants sparingly. Once established, penstemon plants are drought tolerant but will need regular watering until they are established.

Landscaping with Penstemon Flowers

Landscaping with Penstemon is a fantastic way to add long-lasting color and dynamic structure to gardens, attracting a host of pollinators while offering low-maintenance beauty. Known for their vibrant, trumpet-shaped flowers and spiky form, Penstemons can seamlessly fit into various garden themes, enhancing the overall appeal of your outdoor space.

Versatility in Design: Penstemon species come in a range of colors, sizes, and blooming seasons, offering endless possibilities for garden design. From the front of borders to the back, in rock gardens or cottage gardens, these plants can serve as focal points or complementary pieces.

Pollinator-Friendly: These flowers are a favorite among pollinators, including hummingbirds and bees, which are drawn to their nectar-rich blooms. Planting them helps support local ecosystems, contributing to biodiversity.

Drought Tolerance: Many Penstemon varieties are drought-tolerant once established, making them excellent choices for xeriscaping, rock gardens, and other low-water landscapes, particularly in regions with water restrictions or hot, dry climates.

Seasonal Interest: Penstemons have a long blooming season, often from late spring through early fall, providing continuous color when other plants may be waning. The evergreen species also offer visual interest in the garden, even outside the blooming period.

Echinacea paradoxa (Yellow Coneflower, Penstemon barbatus (Red Beardtongue), Salvia sclarea (Clary Sage)

Companion Planting: Their diverse range makes them excellent companions for various other plants. They pair beautifully with ornamental grasses, other wildflowers, and succulents for contrasting textures and forms. They’re also stunning when planted en masse or in swaths for a bold color statement.

Ease of Care: Penstemons generally require minimal care. They don’t need rich soil, and over-fertilizing can, in fact, decrease bloom production. They’re also relatively resistant to pests and diseases, further reducing the need for intervention.

Soil Stabilization: Certain Penstemon species are effective in erosion control, helping stabilize soil on slopes and in areas prone to erosion.

When incorporating Penstemons into your landscape, consider the specific needs of the species you choose in terms of sunlight, soil type, and watering needs. Place them in spots where their vibrant colors and unique shapes can be fully appreciated. Their ability to thrive in challenging soils and conditions also makes them a resourceful option for areas where other plants might struggle.

How to Care for Penstemon

Penstemon, also known as beardtongue, is a group of plants known for their beautiful, tubular flowers and their ability to attract hummingbirds and pollinators. They are relatively easy to care for, making them a favorite among gardeners. Here’s a guide on how to care for Penstemon plants:

Watering: Penstemons are drought-tolerant once established but will need regular water until they reach that point. Water newly planted penstemons regularly until they show signs of growth and are well-established. Once established, water them deeply but infrequently, allowing the soil to dry out between waterings.

Fertilizing: Penstemons do not generally require a lot of fertilizer. Over-fertilizing can lead to abundant leaf growth at the expense of blooms and might even harm the plants. If you choose to fertilize, do so in the fall to help boost their growth and flowering potential.

Mulching: Mulching Penstemon can help regulate ground temperature and suppress weed growth. Choose a mulch that does not hold water. Use organic materials like shredded bark, compost, or pine straw. Avoiding direct contact with the stems to prevent rot and pest issues.

Pruning: Deadhead spent flowers to encourage continued blooming throughout the summer. In late winter or early spring, cut back the plants to about 4-6 inches (10-15 cm) above the ground to promote new growth and help maintain a tidy appearance.

Winter Care: In colder climates, mulch around the base of the plants in fall with straw or another organic material to provide extra insulation from freezing temperatures. Avoid cutting back the plants entirely in the fall; the dead foliage can also provide some extra protection from the cold.

Propagation: Penstemons can be propagated by division, cuttings, or seeds. Division should be done in the spring or fall. Cuttings can be taken in late spring or early summer, while seeds are often sown in the fall or spring, depending on the climate.

Remember, there are several species and varieties of Penstemon, each with its own specific needs. Always check the requirements for the specific type you have in your garden and adjust care as necessary.

Pests and Diseases

Like all plants, Penstemon can be susceptible to certain pests and diseases, although they’re generally considered hardy and trouble-free when their basic growing conditions are met. Here are some of the potential issues you might encounter:

Pests

Aphids: These small, sap-sucking insects can cluster on the undersides of leaves or on stems, potentially transmitting diseases and causing distortion or stunted growth. They can be controlled by rinsing with water, introducing beneficial insects like ladybugs, or using insecticidal soaps.

Spider mites: These tiny mites can be hard to see but cause damage by sucking plant juices, often indicated by yellowing leaves and fine webbing. Mitigate them by ensuring good air circulation, occasional misting to increase humidity, or using miticides if necessary.

Slugs and Snails: These pests are attracted to the moist environment around the plants and can chew holes in the leaves or flowers. Barriers, baits, and manual removal at night can help manage their populations.

Diseases

Root rot: Usually a result of overwatering or poor drainage, symptoms include wilting, yellow leaves, and stunted growth. Prevent it by ensuring well-drained soil and avoiding overwatering.

Powdery mildew: This fungal disease causes a white powdery coating on leaves, stems, and flowers, often occurring in high humidity and moderate temperatures. Improve air circulation, avoid wetting the foliage, and treat with fungicides if necessary.

Rust: This fungal issue presents as orange or brown pustules on the undersides of leaves. Remove affected leaves, avoid overhead watering, and apply a fungicide if severe.

Leaf Spot: This is characterized by brown or black spots on the leaves, often with a yellow halo. Various fungi cause it and can be mitigated by ensuring good air circulation and avoiding overhead watering.

Frequently Asked Questions

Where do penstemons grow best?

Penstemons thrive in areas with full to partial sun and well-draining soil. 

What goes well with Penstemon?

Penstemons pair well with a variety of plants that have similar growing requirements. Good companions include Salvia, Echinacea (coneflowers), Rudbeckia (black-eyed Susans), ornamental grasses, Lavender, and various species of Aster. They also work well in a perennial border with various sages, yarrows, and late spring to summer-blooming bulbs.

What is the easiest Penstemon to grow?

Penstemon eatonii (Firecracker Penstemon) or Penstemon strictus (Rocky Mountain Penstemon) are often recommended for their ease of care, vibrant colors, and adaptability to various conditions.

Are Penstemon fully hardy?

The hardiness of penstemons can vary widely depending on the species. Many are fully hardy in USDA Zones 5-9, though some can survive in colder or warmer zones. It’s essential to check the hardiness rating of the specific variety you’re growing.

What is the most drought-tolerant Penstemon?

Penstemon parryi (Parry’s Penstemon) and Penstemon pseudospectabilis (Desert Penstemon) are known for their drought tolerance, often found in desert or dry, rocky areas.

Which is the most hardy Penstemon?

Penstemon digitalis (Foxglove Beardtongue) and Penstemon hirsutus (Hairy Beardtongue) are among the most cold-hardy, with some varieties rated for USDA Zone 3.