How to Grow Dark Towers Penstemon

Wikimedia Commons

Dark Towers Penstemon

Penstemon × 'Dark Towers'

flower

Dark Towers is a striking hybrid penstemon cultivar prized for its deep burgundy foliage and vibrant tubular flowers that range from red to purple-red. This compact perennial serves as both a foliage plant and prolific bloomer, adding dramatic color to borders and containers. It typically grows 18-24 inches tall and attracts hummingbirds and pollinators throughout the blooming season.

When should you plant Dark Towers Penstemon in your zone?

Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.

Get my Dark Towers Penstemon timeline →

Example Dark Towers Penstemon timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Dark Towers Penstemon

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. First Dark Towers Penstemon blooms

    Around Jun 16

    ≈ 60 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Dark Towers Penstemon dates for your own zip code.

Growing Conditions

☀️
Sun: Full sun, 6-8 hours daily; afternoon shade beneficial in zones 8+
💧
Water: Moderate water during establishment; drought-tolerant once established. Water at base to keep foliage dry. Allow soil to dry between waterings.
📏
Spacing: 12-18 inches
📅
Days to maturity: 60-90 days from transplant to first flowers
🌱
Planting depth: Transplants at soil level; seeds 1/8 inch deep

Soil

Type: Well-draining sandy or gravelly loam
pH: 6.0-7.5
Amendments:
coarse sand perlite gravel compost for organic matter

Growing Zones

Find your zone →

Thrives in zones 4-8, with best performance in zones 5-7

3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b

Sign up free to see if Dark Towers Penstemon grows in your zone — and get a personalized planting timeline.

Get my Dark Towers Penstemon timeline →

Growth Stages

1

Seedling

2-3 weeks

Tiny cotyledons emerge with narrow true leaves following. Foliage begins showing dark burgundy coloring.

Keep soil barely moist, not wet. Provide bright light. Transplant to individual pots at 2-3 true leaves.

2

Vegetative Growth

4-6 weeks

Plant develops compact mounding form with increasing dark burgundy foliage. Stems thicken and branch. No flowers present yet.

Pinch stem tips at 6 inches to encourage bushier growth. Water moderately. Ensure excellent drainage. No fertilizer needed.

3

Budding

2-3 weeks

Flower buds form at stem tips. Deep purple-burgundy foliage fully developed. Plant reaches mature width.

Continue to avoid overwatering. Deadhead any weak buds to direct energy to stronger flowers. Apply light mulch if needed.

4

Flowering

6-10 weeks

Tubular red to deep purple-red flowers open progressively along spikes. Blooms attract hummingbirds. Foliage remains vibrant burgundy.

Deadhead spent flowers to extend bloom. Water at base only. Watch for powdery mildew in humid conditions; ensure good air circulation.

5

Post-Bloom & Winter

2-3 months

Flowering slows as temperatures drop or heat intensifies. Foliage may intensify in color. Plant hardens off for dormancy.

Cut back stems to 6 inches in fall after frost kills foliage. Ensure drainage is excellent to prevent winter rot. Mulch lightly in zones 3-4.

Companion Planting

Plan your garden →

Plant with:

Avoid planting near:

moisture-loving plants like hostas plants requiring frequent watering mint

Common Pests

  • Ensure good air circulation, avoid wetting foliage, remove infected leaves, apply sulfur dust if severe, thin crowded stems

  • Spray with water to increase humidity, use neem oil, improve air circulation, monitor undersides of leaves

  • Yellow sticky traps, insecticidal soap, encourage natural predators, remove heavily infested leaves

  • Improve drainage immediately, reduce watering, repot in dry soil if in containers, remove affected portions

Uses

🍳

Hummingbird Nectar Source

Culinary

The tubular flowers are rich in nectar and actively visited by hummingbirds and other pollinators, making it an excellent plant for wildlife gardens and attracting these beneficial visitors. [source]

🎨

Cut Flower Arrangements

Craft

The striking flower spikes and burgundy foliage make excellent long-lasting cut flowers for fresh arrangements, dried arrangements, and floral design. [source]

🏠

Ornamental Border and Container Plant

Household

Dark Towers excels as a focal plant in perennial borders, rock gardens, containers, and drought-tolerant landscapes, providing multi-season interest with both foliage and flowers. [source]

🦋

Pollinator Garden

Wildlife

A premier choice for attracting native bees, butterflies, and hummingbirds while providing a long season of nectar-rich blooms from early summer through fall. [source]

🏠

Xeriscape and Low-Water Landscaping

Household

Once established, Dark Towers is extremely drought-tolerant and requires minimal water and maintenance, making it ideal for water-wise gardens and sustainable landscapes. [source]

Harvest Tips

Not typically harvested as Dark Towers is an ornamental flower. Deadhead spent blooms to encourage continuous flowering throughout the season. Cut back entire plant to 6 inches after first frost in fall. Collect seeds from dried flowers in late summer if desired for propagation.

Fun Facts

  • 🌱 Dark Towers was bred by Mt. Cuba Center and is a hybrid of Penstemon digitalis and Penstemon barbatus, combining vigor with ornamental appeal.
  • 🌱 The deep burgundy foliage intensifies in color during cooler weather and bright sunlight, making it a true four-season plant in many regions.
  • 🌱 Penstemons are sometimes called 'beardtongue' because their stamens are covered with fine hairs, and they are among the best native plants for attracting western hummingbird species.

Gardening Terms

New to gardening? Learn about terms used in this guide:

Join 30,000 gardeners planning their gardens with LizPlants.

Get your personalized Dark Towers Penstemon planting timeline

Tell us your zip code and we'll calculate exactly when to start Dark Towers Penstemon seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.

Get my Dark Towers Penstemon timeline →