Penstemon campanulatus 'Garnet' (Penstemon) — Bushy, upright, semi-woody at the base

Overview

Penstemon campanulatus 'Garnet' is a bushy, upright, semi-woody at the base perennial in the genus Penstemon, part of the Plantaginaceae family, with semi-evergreen or evergreen; narrow, glossy, mid to dark green foliage. Penstemon campanulatus 'Garnet' grows best in full sun, and tolerates most soils and neutral to alkaline pH. Its UK hardiness is rated H3-H5. Suggested uses include borders, rock gardens, cottage gardens and pollinator-friendly gardens. It is native to Western North America.

About

Penstemon campanulatus 'Garnet' is a perennial in the Plantaginaceae that offers an extended summer display from June to September. It grows upright and well-branched with a semi-woody base and narrow, glossy mid to dark green leaves that are semi-evergreen or evergreen in milder sites. Position it in full sun on a south- or west-facing, sheltered spot in light, fertile, free-draining loam or sand to avoid winter wet.

About the genus

Penstemon, the beardtongues, is a large genus of roughly 280 species of flowering plants native to North America from northern Canada to Central America. It is the largest genus of flowering plants endemic to North America. As well as being the scientific name, penstemon is also widely used as a common name for all Penstemon species alongside beardtongues.

Wikipedia contributors, "Penstemon", CC BY-SA 4.0 — Penstemon

In the garden

Penstemon campanulatus 'Garnet' is a North American perennial from western regions of the continent and sits in the Plantaginaceae. It carries narrow, glossy leaves that remain semi-evergreen or evergreen where winters are mild and develops an upright, well-branched habit with a semi-woody base. Flowering runs from June to September, providing an extended period of interest through the summer months. Give it full sun on a south- or west-facing site with some shelter from prevailing winds. It prefers light, fertile, free-draining loam or sandy soils with a neutral to alkaline pH; standing water in winter is the common cause of losses, so good drainage is essential. Hardiness is rated H3–H5: H3 is borderline in the coldest inland spots, H4 indicates average garden hardiness and H5 denotes hardy conditions. In practice it performs best where soil dries out over winter and plants are protected from severe exposure. Use Penstemon campanulatus 'Garnet' in mixed borders, rock gardens, cottage-style beds or pollinator-friendly schemes where a sunny, sheltered site is available. Its semi-woody basal growth helps the plant keep structure through winter on protected sites.

Growing conditions

Best soil and position for Penstemon

Sunlight: Full sun
Soil type: Light, fertile, free-draining loam or sand
Soil pH: Neutral to alkaline
Soil moisture: Well drained; winter wet causes most losses
Aspect: South or west facing
Exposure: Sheltered
UK hardiness: H3-H5

Plant details

Penstemon campanulatus 'Garnet' size, habit and characteristics

Plant type: Perennial
Habit: Bushy, upright, semi-woody at the base
Foliage: Semi-evergreen or evergreen; narrow, glossy, mid to dark green
Suggested uses: Borders, rock gardens, cottage gardens, pollinator-friendly gardens
Native to: Western North America

Care notes

Pruning and caring for Penstemon campanulatus 'Garnet'

Cultivation: Drainage and shelter decide whether a penstemon is perennial or annual in your garden. Plant in spring rather than autumn so the roots establish before winter, and leave the top growth standing until spring as crown protection. Regular deadheading is what sustains the extraordinarily long season. Given the modest hardiness of most cultivars, taking cuttings every summer is sensible insurance.
Pruning: Leave stems intact over winter, then cut back to low healthy buds in mid-spring once frosts have passed. Deadhead continuously through summer, cutting spent spikes to a side shoot.
Propagation: Semi-ripe cuttings taken in late summer root quickly and are the standard method - and the usual replacement for winter losses. Species can be raised from seed.
Pest resistance: Slugs take young spring shoots; capsid bug and eelworm occur but are uncommon.
Disease resistance: Powdery mildew and leaf spot appear on crowded plants. Root rot follows winter waterlogging.

Frequently asked questions

How do I grow Penstemon campanulatus 'Garnet'?

Drainage and shelter decide whether a penstemon is perennial or annual in your garden. Plant in spring rather than autumn so the roots establish before winter, and leave the top growth standing until spring as crown protection. Regular deadheading is what sustains the extraordinarily long season. Given the modest hardiness of most cultivars, taking cuttings every summer is sensible insurance.

Where is the best place to plant Penstemon campanulatus 'Garnet'?

Penstemon campanulatus 'Garnet' prefers full sun. It suits sheltered positions.

What soil does Penstemon campanulatus 'Garnet' need?

Penstemon campanulatus 'Garnet' is adaptable and grows happily in most soil types, including light, fertile and free-draining loam or sand. It prefers neutral to alkaline soil. Aim for soil that stays well drained; winter wet causes most losses.

How do I prune Penstemon campanulatus 'Garnet'?

Leave stems intact over winter, then cut back to low healthy buds in mid-spring once frosts have passed. Deadhead continuously through summer, cutting spent spikes to a side shoot.

Is Penstemon campanulatus 'Garnet' hardy in the UK?

Penstemon campanulatus 'Garnet' has an RHS hardiness rating of H3, meaning it is half-hardy, tolerating -5 to 1°C, and may need winter protection in colder areas.

How do I propagate Penstemon campanulatus 'Garnet'?

Semi-ripe cuttings taken in late summer root quickly and are the standard method - and the usual replacement for winter losses. Species can be raised from seed.

More in the Penstemon genus

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