Foxglove Beardtongue, scientifically known as Penstemon digitalis, is a striking perennial plant. This North American native boasts elegant, bell-shaped white flowers, often with a hint of pink or lavender and purple-veined throats, on tall, upright reddish stems. Its common name refers to its resemblance to true foxglove (Digitalis purpurea), though Penstemon digitalis is not toxic like its European counterpart. It attracts various pollinators, including long-tongued bees and hummingbirds. Its hardiness and ease of cultivation make it a popular choice for many gardeners.
Choosing the Right Spot and Planting
Light Requirements
Foxglove Beardtongue thrives in full sun, meaning at least six hours of direct sunlight daily. It can tolerate partial shade, receiving four to six hours of direct sun. Ample sunlight encourages abundant flowering. In warmer climates, afternoon shade can prevent stress.
Soil Needs
Well-drained soil is crucial for Foxglove Beardtongue, as it is highly susceptible to root rot in overly wet conditions. The plant adapts to various soil types, including loamy, sandy, or clay loam, provided they offer good drainage. A slightly acidic to neutral soil pH (5.5-7.0) is preferred. Incorporating organic matter like compost or grit can improve drainage in heavier clay soils.
How to Plant
When planting Foxglove Beardtongue, space plants 12 to 24 inches apart. Set the plant crown at soil level, avoiding deep burial. After placement, thoroughly water the plant and surrounding soil to help it settle. Consistent moisture is important during the initial establishment period, typically for a few weeks.
Routine Care and Upkeep
Watering Practices
Once established, Foxglove Beardtongue is drought tolerant. For optimal growth and flowering, maintain medium soil moisture, especially during prolonged dry spells. Allow the soil to dry out partially between waterings to prevent root rot. Overwatering is detrimental, as the plant does not tolerate continually wet conditions.
Fertilization
Foxglove Beardtongue is not a heavy feeder and thrives without extensive fertilization. If you choose to fertilize, apply a light, balanced, slow-release fertilizer in spring or an organic fertilizer in fall. Avoid over-fertilizing, as this can lead to excessive foliage growth at the expense of flowers or make the plant prone to flopping.
Pruning and Deadheading
Deadheading, the removal of spent flowers, encourages more blooms, extends the flowering period, and prevents unwanted self-seeding. Simply clip faded flower stalks back. Beyond deadheading, minimal pruning is needed, primarily to remove damaged or diseased foliage. Some gardeners cut back the entire plant in late autumn or early spring for a tidier look.
Dealing With Common Issues
Pests and Diseases
Foxglove Beardtongue is generally resistant to most serious pests and diseases, making it a low-maintenance plant. Aphids might appear on stems but typically cause no significant damage. Fungal diseases like powdery mildew or leaf spot can occur with poor air circulation or excessive humidity. Ensure good air circulation and avoid overhead watering to prevent these problems.
Other Growth Problems
Foxglove Beardtongue may exhibit flopping stems. This can be caused by too much shade, leading to leggy growth, or by overly rich soil and excessive fertilization promoting weak growth. Ensure adequate sunlight and avoid heavy fertilization to maintain an upright habit. A lack of blooms often indicates insufficient sunlight. Yellowing leaves during dry periods can signal insufficient moisture, remedied with supplemental watering.
Preparing for Winter
Foxglove Beardtongue is a hardy perennial, thriving in USDA Hardiness Zones 3 through 8. In colder climates, its semi-evergreen basal foliage may persist through winter, often developing purplish hues. For winter care, gardeners have two options: leave spent foliage and stalks standing for winter interest and crown protection, or cut the plant back in late autumn or early spring. In very cold regions, apply a light layer of organic mulch, like shredded bark or compost, around the plant’s base in late fall for root insulation. Ensure mulch does not touch stems to prevent rot.