Penstemon (Beardtongue)

Why Should I Grow Penstemon?

Growing Penstemon in your garden, landscape, or natural area offers a multitude of benefits:

Aesthetic Appeal: With their vibrant, tubular flowers, Penstemons add a splash of color and visual interest to any garden. The variety in species offers a range of colors, sizes, and forms, allowing for diverse and creative garden designs.

Attract Pollinators: Penstemons are known for their ability to attract a variety of pollinators. Their nectar-rich flowers are favorites for bees, butterflies, and hummingbirds, which can help maintain the health of your garden and promote biodiversity.

Drought Tolerance: Many Penstemon species are particularly drought-tolerant, making them excellent choices for low-water gardens and xeriscaping. Once established, they require minimal water, suiting areas with water restrictions or those wishing to conserve water.

Ease of Care: Generally, Penstemons are low-maintenance plants. They don’t require complex soil amendments and, once established, can thrive with minimal care, making them suitable for both new and experienced gardeners.

Penstemon cardwellii & Castilleja miniata. Mount St Helens National Park, Washington State

Erosion Control: Certain species of Penstemon have a growth habit that makes them effective for erosion control. They can stabilize soil on slopes and in areas prone to erosion.

Adaptability: Penstemons can thrive in a variety of soil types and climatic conditions, making them adaptable to various environments. There’s likely a Penstemon that can thrive in your specific region and soil conditions.

Native Plant Benefits: Using native Penstemons enhances the natural ecosystem, providing food and habitat for local wildlife. Native plants often have a better survival rate in their local environment and contribute to the biodiversity and ecological health of their region.

Seasonal Interest: Many Penstemons have an extended blooming season, providing color and interest in the garden for a longer period compared to other perennials. Some even have attractive foliage or seed pods for fall and winter interest.

Versatility: Penstemons work well in various garden types, from formal and casual flower beds to wildflower meadows and naturalistic landscapes. They can be used as border plants, specimens, or ground covers, depending on the species.

Low Pest and Disease Issues: Penstemons are typically resistant to many pests and diseases, especially when planted in conditions that suit their growth needs.

Popular Penstemon Varieties

There are numerous varieties of Penstemon, each with unique characteristics. Here are brief descriptions of some main varieties:

Penstemon digitalis (Foxglove Beardtongue): A remarkable perennial prized for its tubular white flowers and statuesque presence in the landscape. It is suitable for the perennial border, the natural landscape or prairie reconstructions.

Penstemon eatonii (Firecracker Penstemon): Recognizable by its bright scarlet-red flowers, this variety is extremely drought-tolerant and a hummingbird magnet.

Penstemon heterophyllus (Foothill Beardtongue): Offers electric blue to violet flowers, often with contrasting foliage. Drought-tolerant and vibrant, it’s a favorite for xeriscapes.

Penstemon palmeri (Scented Penstemon): Known for its large, fragrant, pale pink to rose-colored flowers, Penstemon palmeri, or Palmer’s penstemon, is a native desert species, attracting hummingbirds and providing a striking vertical element with its tall, erect stems.

Penstemon speciosus (Royal Penstemon): Boasts charming wands of royal blue flowers in late spring to mid-summer. It is a good plant for water-wise landscaping, rock gardens, desert gardens, and other ornamental plantings.

Penstemon spectabilis (Showy Beadtongue): Showcases vivid purple-blue flowers on erect spikes, a beacon for pollinators. It’s valued for drought resistance, making it a staple in water-wise gardens and native Californian landscapes.

Penstemon strictus (Rocky Mountain Beardtongue): Showcases deep violet-blue flowers. Hardy and beautiful, it’s native to the meadows and slopes of the Rocky Mountains.

Penstemon ‘Husker Red’: Popular for its white flowers and unique, reddish-purple foliage, providing dramatic color contrast in gardens.

Penstemon ‘Dark Towers‘: A hybrid prized for its pink flowers and dark wine-purple foliage, taller and more disease-resistant than ‘Husker Red’.

Garden Design with Penstemon

Incorporating Penstemon in your garden design can add remarkable texture, color, and an attraction for wildlife like birds and butterflies. Here’s how you can design your garden with Penstemon:

Color Palette: Penstemons bloom in a variety of colors including pink, red, white, blue, and purple. Determine your garden’s color scheme first; then select the variety of Penstemon that complements it. For a warmer palette, go for reds and pinks. For cooler tones, choose blues and purples.

Borders and Beds: Penstemon plants are excellent for borders and flower beds, as they can add height and structure, especially the taller varieties. Plant them in groups or drifts for visual impact, or use them as a repeating element to create rhythm and coherence in your garden design.

Wildlife Attraction: Because they’re known for attracting pollinators, place Penstemons in a sunny spot where you can observe the birds, bees, and butterflies that they draw. They’re especially known for attracting hummingbirds.

Container Gardening: Some compact varieties of Penstemon are well-suited to container gardening. This is a great way to adorn patios, balconies, and entryways. Ensure the containers have adequate drainage and are large enough to support the plant’s growth.

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

Rock Gardens and Xeriscaping: Drought-resistant Penstemons are perfect for rock gardens and xeriscaping. Their ability to thrive in less-than-ideal soil makes them a fantastic low-maintenance choice for these types of landscapes.

Companion Planting: Penstemon plants are highly compatible with other perennials. Consider planting them with complementary species such as lavender, salvia, or ornamental grasses for contrasting textures. 

Vertical Interest: Taller varieties of Penstemon can add vertical interest to your garden. They can act as a colorful backdrop for shorter plants or be used as focal points.

Cottage Gardens: Penstemon works well in a cottage garden setting, offering a blend of shapes and colors that contribute to the overall charming effect. They can be mixed with traditional cottage garden plants like roses, foxgloves, and phlox.

Sustainable Landscaping: Native varieties of Penstemon are an excellent choice for sustainable landscapes due to their low water needs and attraction of beneficial wildlife.

Growing and Caring for Penstemon

Growing and caring for Penstemon involves understanding their needs for sunlight, soil, water, pruning, and general maintenance. Here’s how you can ensure your Penstemon thrives:

Planting Location: Most Penstemon species prefer a location with full sun but can tolerate partial shade, especially in hotter climates. Around 6-8 hours of sunlight is ideal. Ensure good air circulation around the plants to prevent fungal diseases.

Soil: Penstemons thrive in well-drained soil. They can tolerate a wide range of soil types, including sandy, loamy, or rocky soils, but they generally don’t do well in heavy clay or overly rich soils.

Watering: These plants are drought-tolerant once established but will need regular water until they reach that point. Water deeply when the soil is dry to the touch, but allow the soil to dry out slightly between waterings. Overwatering or constant soil moisture can lead to root rot, a common issue with Penstemons.

Fertilization: Penstemons generally do not require much fertilizer. Overfeeding can lead to lush foliage but fewer flowers and can also make the plants leggy and weak. However, providing them with a light application of an organic fertilizer in the fall can help boost their growth and flowering potential.

Pruning and Deadheading: Regular deadheading (removing spent flowers) can encourage a longer blooming period. In late winter or early spring, prune back any dead or damaged stems to make way for new growth. 

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.

Winterizing: While many Penstemons are perennials, they can be sensitive to harsh winters, especially in very cold climates. Mulching around the base can help protect the roots. In colder zones, consider winter protection such as straw or a frost cloth, especially for less hardy varieties.

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.

By paying attention to these aspects of their care, you can enjoy the beauty of Penstemon flowers in your garden for many years. Remember, the specific needs can vary slightly between different species and cultivars, so always check the requirements for the particular type of Penstemon you are growing.

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

Can you overwater Penstemon?

Yes, you can overwater penstemons. They are drought-tolerant plants that prefer well-drained soils. Overwatering can lead to root rot, a condition that occurs when the plant’s roots sit in water for too long, depriving them of necessary oxygen. Symptoms of overwatering include yellowing leaves, wilting, and a stunted or mushy base. It’s best to let the soil dry out between waterings to prevent these issues.

Should I deadhead my Penstemons?

Yes, it would be best if you deadheaded penstemons. Deadheading, or removing spent flowers, encourages the plant to produce more blooms and extends the flowering season. It also prevents the plant from using its energy to produce seed, focusing more on vegetative growth and future flowers.

Why is my Penstemon floppy?

Penstemon stems can become floppy for several reasons. Overwatering, too much fertilizer, or not enough sunlight can lead to lush but weak, leggy growth. Lack of pruning can also result in long, overgrown stems that can’t support themselves. To prevent floppiness, ensure your penstemon is planted in well-drained soil, gets plenty of sunlight, and is not over-fertilized. Regular pruning, including cutting back in the early spring, can help promote bushier, more stable growth.

Should Penstemon be staked?

Staking penstemons is not usually necessary, as they are generally upright plants. However, if they are planted in a particularly windy area, have been over-fertilized leading to excessive growth, or if they’re flopping due to any of the reasons mentioned above, staking might be necessary to prevent breakage and keep them upright. Use a stake that is the height of the plant minus the flower head and tie the stem to the stake loosely with garden twine. Stakes should be inserted when the plants are small to avoid root damage. Regular pruning to encourage bushier growth can reduce the need for staking in the future.