Penstemon ‘Garnet’ – Growing Guide & Care Tips for Long‑Lasting Colour

Penstemon ‘Garnet’ is a striking perennial with vivid tubular flowers that bring rich colour to borders from late spring through summer. This guide covers the best planting locations, watering, pruning, winter care, and growing tips to help your Penstemon thrive.

1. Planting Location

Sunlight:
Full sun to partial shade, ideally 6–8 hours of direct sun.

Soil:

• Well‑draining sandy or loamy soils
• Avoid heavy clay or consistently wet areas

pH: Slightly acidic to neutral (6.0–7.0).

Good drainage is the key to long‑lived Penstemons.

2. Planting Instructions

Best Time to Plant:

• Spring
• Autumn (especially in milder climates)

Spacing:
Place plants 12–18 inches apart to ensure airflow and healthy growth.

Depth:
Dig a hole twice the width of the root ball and plant at the same depth as in the pot.

3. Watering

After Planting:
Water thoroughly to settle the soil around the roots.

Ongoing Care:

• Water during dry spells
• Allow soil to dry out between waterings
• Avoid constantly wet soil

Penstemons are naturally drought-tolerant once mature.

4. Fertilising

Use a balanced, slow‑release fertiliser in early spring.
A single application is usually enough for strong flowering.

Avoid heavy feeding — it encourages leafy growth instead of blooms.

5. Pruning & Deadheading

During the Season:
Remove spent flowers to extend the bloom period.

Autumn / Winter:
Cut plants back to around 6 inches after the first frost.

This keeps the plant tidy and ready for fresh spring growth.

6. Pests & Diseases

Common pests include:

• Aphids
• Spider mites

Control with insecticidal soap or natural predators.

Powdery mildew can develop in poor air circulation.
Space plants well and avoid overhead watering.

7. Winter Care

Hardy to Zones 4–8.

In colder areas:

• Apply a layer of mulch to protect the roots
• Use well-rotted compost or bark mulch

Drainage is essential — waterlogged soil is the biggest winter risk.

8. Propagation

You can propagate Penstemon ‘Garnet’ by:

• Seed
• Division

Best time for division:
Spring or autumn when the plant is dormant or lightly active.

9. Companion Plants

Perfect alongside:

• Salvia
• Echinacea
• Rudbeckia

These combinations create a vibrant, pollinator‑friendly summer border.

10. Extra Growing Tips

• Regular deadheading boosts flowering
• Monitor moisture in hot weather
• Keep soil free‑draining for longevity

FAQs

Is Penstemon ‘Garnet’ easy to grow?

Yes — it’s a low‑maintenance, hardy perennial suitable for most UK gardens.

How tall does Penstemon ‘Garnet’ get?

Typically 60–90cm with upright flowering stems.

Does Penstemon ‘Garnet’ attract pollinators?

Absolutely — bees love its tubular blooms.

Can I grow it in partial shade?

Yes, but flowering is best in full sun.

Should I mulch Penstemon in winter?

Yes, a light mulch helps protect roots in colder areas.

When should I prune it back?

Cut back to 6 inches after the first frost or in early spring.