Foxglove Beardtongue Companion Plant Height Management

Understanding Foxglove Beardtongue (Penstemon digitalis)

Foxglove Beardtongue, scientifically known as Penstemon digitalis, is a stunning native North American perennial celebrated for its elegant spires of white to pale pink, tubular flowers that bloom in late spring to early summer. Often referred to as “Foxglove” due to the resemblance of its blossoms to those of the European Foxglove (Digitalis purpurea), it’s crucial to note that Penstemon digitalis is non-toxic, unlike its namesake. This hardy plant is a magnet for pollinators, including bees, butterflies, and hummingbirds, making it an invaluable addition to any pollinator-friendly garden.

Its upright growth habit and attractive foliage, which can develop reddish hues in the fall, add structural interest to the landscape throughout the growing season. While generally well-behaved, understanding its growth habits and how to manage its height is key to integrating it harmoniously with other garden companions. This guide will explore effective companion planting strategies and practical height management techniques for Foxglove Beardtongue, ensuring a beautiful and balanced garden.

Key Characteristics of Foxglove Beardtongue

Before delving into companion planting and height management, let’s review the essential characteristics of Penstemon digitalis:

• Scientific Name: Penstemon digitalis
• Common Names: Foxglove Beardtongue, Smooth White Penstemon, Tall Beardtongue
• Bloom Time: Late Spring to Early Summer
• Flower Color: White to Pale Pink, often with subtle purple veining
• Height: Typically 2-4 feet (60-120 cm)
• Spread: 1-2 feet (30-60 cm)
• Sunlight Needs: Full Sun to Partial Shade
• Soil Preferences: Adaptable, but prefers well-drained, moist to average soils. Tolerates clay and sandy soils.
• Hardiness Zones: 3-8
• Pollinator Attraction: Highly attractive to bees, butterflies, and hummingbirds.
• Drought Tolerance: Moderate once established.
• Toxicity: Non-toxic

Companion Planting with Foxglove Beardtongue

Companion planting is a horticultural practice that involves growing different plants in proximity to each other, leveraging their natural interactions to enhance growth, deter pests, attract beneficial insects, or improve soil health. For Foxglove Beardtongue, selecting companions that share similar growing conditions and complement its aesthetic appeal is paramount.

Choosing Companions Based on Growing Conditions

Penstemon digitalis thrives in full sun to partial shade and prefers well-drained soil. When selecting companions, aim for plants that have comparable needs regarding sunlight, water, and soil type. This ensures that all plants in the grouping receive optimal conditions for health and vigor.

Sunlight Requirements

• Full Sun Companions: Plants that flourish in at least six hours of direct sunlight daily.
• Partial Shade Companions: Plants that tolerate dappled shade or a few hours of direct sun, particularly in the hottest part of the afternoon.

Soil and Moisture Preferences

• Well-Drained Soil: Essential for preventing root rot.
• Moist to Average Soil: While it tolerates dry spells once established, it performs best with consistent moisture. Avoid waterlogged conditions.

Aesthetic Companionship: Balancing Form and Color

Beyond shared growing needs, consider how companion plants will visually complement Foxglove Beardtongue. Its upright, airy flower spikes can be paired with plants that offer contrasting textures, shapes, and colors to create a dynamic and visually appealing garden bed.

Complementary Color Palettes

• Cool Colors: Blues, purples, and silvers can create a serene and sophisticated contrast with the white and pink blooms.
• Warm Colors: Yellows, oranges, and reds can create a vibrant and energetic display, especially when strategically placed.
• Greens: Various shades of green foliage provide a lush backdrop and can anchor the more colorful blooms.

Contrasting Textures and Forms

• Mounding Plants: Low-growing, bushy perennials can fill in the space around the base of the Foxglove Beardtongue, providing a fuller look.
• Grasses: Ornamental grasses offer fine texture and movement, creating a beautiful interplay with the solid flower stalks.
• Foliage Plants: Plants with interesting leaf shapes and colors can add visual interest even when the Foxglove Beardtongue is not in bloom.

Recommended Companion Plants for Foxglove Beardtongue

Here are some excellent companion plant choices, categorized by their typical height and bloom time relative to Foxglove Beardtongue:

Low-Growing Companions (Groundcovers and Fillers)

These plants will spill around the base of the Penstemon digitalis, adding texture and color.

• Creeping Thyme (Thymus serpyllum): Aromatic, low-growing groundcover that thrives in sun and well-drained soil.
• Catmint (Nepeta spp.): Mounding perennial with fragrant foliage and lavender-blue flowers, attracting pollinators.
• Coral Bells (Heuchera spp.): Offers a variety of colorful foliage, from deep purple to lime green, and airy flower stalks. Prefers some shade.
• Pinks (Dianthus spp.): Low-growing, often fragrant flowers in shades of pink, red, and white.

Mid-Height Companions (Similar Bloom Time or Height)

These plants will intermingle with the Foxglove Beardtongue, creating a layered effect.

• Coneflower (Echinacea spp.): Daisy-like flowers in shades of pink, purple, and white that bloom simultaneously and attract pollinators.
• Black-Eyed Susan (Rudbeckia hirta): Bright yellow to orange flowers that provide a cheerful contrast.
• Salvia (Salvia spp.): Many varieties offer spikes of blue, purple, or pink flowers and are excellent for attracting pollinators.
• Yarrow (Achillea spp.): Flat-topped clusters of flowers in a range of colors, adding a feathery texture.
• Coreopsis (Coreopsis spp.): Cheerful, daisy-like flowers in yellow and orange, blooming throughout summer.

Taller Companions (Background or Structural Elements)

These can be planted behind or alongside the Foxglove Beardtongue for added height and visual depth.

• Blazing Star (Liatris spp.): Tall, feathery spikes of purple flowers, a favorite of butterflies.
• Joe-Pye Weed (Eutrochium spp.): Tall, robust plants with large, domed clusters of pink or purple flowers in late summer.
• Bee Balm (Monarda spp.): Whimsical, spiky flowers in shades of red, pink, and purple, a hummingbird favorite.
• Ornamental Grasses (e.g., Little Bluestem, Switchgrass): Provide fine texture, movement, and winter interest.

Height Management for Foxglove Beardtongue

While Penstemon digitalis typically reaches 2-4 feet, its height can be influenced by growing conditions. In very fertile soil or with excessive moisture, it might grow taller and potentially become leggy. Conversely, in lean or dry conditions, it might remain shorter. Effective height management ensures the plant maintains a desirable, well-proportioned form within the garden design.

Pruning Techniques

Pruning is the most direct method of controlling plant height and encouraging bushier growth.

Deadheading

Removing spent flower stalks, known as deadheading, encourages the plant to produce more blooms and prevents it from expending energy on seed production. This can also subtly influence overall height by promoting a more compact, multi-branched form rather than a single, tall spike.

• When to Deadhead: As soon as flowers begin to fade and before they set seed.
• How to Deadhead: Cut the entire flower stalk back to a leaf node or to the ground if the foliage is unappealing.

Cutting Back After Blooming

For a tidier appearance and to encourage a possible second flush of blooms, you can cut back the entire plant after its initial bloom cycle.

• When to Cut Back: Mid-summer, after the main flowering period is over.
• How to Cut Back: Trim the plants back by about one-third to one-half of their height. This often stimulates new growth and can lead to a shorter, denser plant.

Spring Pruning

While many gardeners prefer to leave the dried seed heads for winter interest and to provide food for birds, you can also cut back the foliage in early spring.

• When to Prune: In early spring, before new growth begins.
• How to Prune: Cut back all dead foliage from the previous year. This can be done by cutting the entire clump down to a few inches above the ground. This tidies the plant and makes way for the fresh new growth.

Cultural Practices

Beyond direct pruning, certain cultural practices can influence the plant’s natural height.

Fertilization

Foxglove Beardtongue is not a heavy feeder. Over-fertilizing, especially with high-nitrogen fertilizers, can lead to rapid, weak, and leggy growth, increasing the plant’s susceptibility to flopping and disease.

• Recommendation: Avoid fertilizing unless your soil is extremely poor. If you do fertilize, use a balanced, slow-release organic fertilizer in early spring sparingly.

Watering

While it appreciates consistent moisture, overly wet conditions, especially combined with rich soil, can promote taller, weaker growth.

• Recommendation: Ensure excellent drainage. Water deeply but infrequently once the plant is established, allowing the soil to dry slightly between waterings.

Division

As Foxglove Beardtongue matures, clumps can become dense and may benefit from division. This process can rejuvenate the plant and, by extension, influence its growth habit, potentially leading to more manageable heights.

• When to Divide: In early spring or fall.
• How to Divide: Carefully dig up the clump, separate it into smaller sections, ensuring each section has healthy roots and shoots, and replant them at the appropriate depth.

Strategic Placement

The location where you plant Foxglove Beardtongue can also play a role in managing its perceived height.

• Front of Border: Planting it towards the front of a mixed border might make its height seem more prominent.
• Mid to Back of Border: Placing it in the middle or back allows it to blend with taller companions and creates a layered effect, reducing the visual impact of its individual height.
• Grouping: Planting in groups of three or more can create a more substantial visual impact, making the individual plant height less of a concern.

Troubleshooting and Maintenance

Even with careful planning, some issues can arise. Understanding common problems and their solutions will help maintain a healthy and attractive Foxglove Beardtongue.

Flopping or Staking

If your Foxglove Beardtongue becomes leggy due to excessive fertility, shade, or lack of pruning, it may start to flop.

• Solutions:

Pruning: As described above, cutting back can encourage bushier, more upright growth.
Staking: For particularly tall or weak stems, discreet staking with bamboo stakes or plant supports can be used to maintain an upright form.
Hard Pinching: In early spring, before growth really takes off, pinching back the tips of new shoots can encourage branching and a more compact habit.

Pest and Disease Resistance

Foxglove Beardtongue is generally quite resistant to pests and diseases.

• Common Issues: Occasionally, powdery mildew can affect the foliage, especially in humid conditions or with poor air circulation. Slugs and snails might nibble on young foliage.
• Solutions:

Powdery Mildew: Ensure good air circulation by spacing plants appropriately. Avoid overhead watering. Fungicides can be used as a last resort.
Slugs and Snails: Use slug bait, beer traps, or handpick them in the early morning or evening. Planting companions that deter slugs, like rue or yarrow, can also help.

Key Facts and Comparison Table

To summarize the core information and provide a quick reference for choosing companions and managing height, here is a comparative table.

Foxglove Beardtongue & Potential Companions at a Glance

Plant	Typical Height	Bloom Time	Sunlight Needs	Soil Needs	Height Management Considerations
Foxglove Beardtongue (Penstemon digitalis)	2-4 ft (60-120 cm)	Late Spring-Early Summer	Full Sun-Partial Shade	Well-drained, moist to average	Prune spent blooms, cut back after flowering, avoid over-fertilizing.
Coneflower (Echinacea spp.)	2-5 ft (60-150 cm)	Summer	Full Sun	Well-drained, average to dry	Deadhead for rebloom, can be cut back in fall.
Salvia (Salvia spp.)	1-4 ft (30-120 cm)	Summer-Fall	Full Sun	Well-drained, average to dry	Pinch back in early summer for bushier growth, deadhead for rebloom.
Yarrow (Achillea spp.)	1-3 ft (30-90 cm)	Summer	Full Sun	Well-drained, average to dry	Cut back after first bloom for a tidier appearance and potential second bloom.
Catmint (Nepeta spp.)	1-3 ft (30-90 cm)	Summer-Fall	Full Sun	Well-drained, average to dry	Shear back after first bloom to encourage repeat flowering and a compact shape.

Steps for Successful Integration and Height Management

Implementing a successful companion planting strategy for Foxglove Beardtongue involves a few key steps. This table outlines the process, along with the pros and cons of certain management techniques.

Integrating Foxglove Beardtongue & Height Management Strategies

Step	Description	Pros	Cons
1. Site Selection & Preparation	Choose a location with full sun to light shade and well-drained soil. Amend soil if necessary with compost.	Ensures optimal growth conditions for all plants.	Requires assessing existing soil conditions.
2. Companion Plant Selection	Select companions based on similar sunlight, soil, and moisture needs, considering aesthetic appeal (color, texture, form).	Creates a harmonious and visually appealing planting. Promotes plant health through shared conditions.	Requires knowledge of various plant needs.
3. Planting Strategy	Arrange plants, considering mature sizes. Place taller companions behind shorter ones, and use low-growing plants as groundcover.	Optimizes space and visual balance. Prevents overcrowding.	Requires careful planning and spacing.
4. Initial Watering & Mulching	Water newly planted specimens thoroughly. Apply a layer of mulch to retain moisture and suppress weeds.	Aids in establishment and reduces maintenance.	Mulch needs occasional replenishment.
5. Height Management: Deadheading	Remove spent flower stalks as they fade.	Encourages rebloom, prevents unwanted seeding, promotes a tidier appearance.	Requires regular monitoring during bloom.
6. Height Management: Cut Back After Bloom	Cut back plants by about one-third to one-half after the main flowering period.	Promotes a bushier habit, can encourage a second, smaller bloom cycle, maintains a more compact form.	May slightly reduce overall plant mass if cut too severely.
7. Height Management: Spring Pruning	Cut back all dead foliage to a few inches above the ground in early spring.	Tidies the plant for the new season, removes potential overwintering pests/diseases.	Removes winter interest (dried flower stalks).
8. Fertilization (Minimal)	Avoid excessive fertilization. Use a balanced organic fertilizer only if soil is very poor.	Prevents leggy, weak growth and promotes natural, sturdy habit.	Requires awareness of soil fertility levels.

Conclusion

Foxglove Beardtongue (

Penstemon digitalis*) is a valuable and beautiful native perennial that offers significant benefits to any garden, especially those focused on supporting pollinators. By understanding its growth habits and employing strategic companion planting and height management techniques, you can ensure this stunning plant thrives, adding its elegant floral display and structural interest to your landscape for years to come. Choosing companions with similar needs and embracing judicious pruning and careful cultural practices will lead to a healthy, balanced, and visually captivating garden.