Penstemon 'Rubicunda' (Beardtongue) — Bushy, upright, semi-woody at the base

Overview

Penstemon 'Rubicunda' 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 'Rubicunda' grows best in full sun, and tolerates most soils and neutral to alkaline pH. Its UK hardiness is rated H3-H5.

About

Penstemon 'Rubicunda' is a perennial in the Plantaginaceae with a well-branched, upright habit and a semi-woody base. It bears narrow, glossy mid to dark green leaves that remain semi‑evergreen in milder sites. The plant produces the genus-typical two-lipped, tubular flowers from June to September. Best grown in full sun on light, free-draining neutral to alkaline soils in a sheltered south or west-facing position.

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 'Rubicunda' belongs to the genus Penstemon and originates from North America, where members of the genus form narrow-leaved, tubular-flowered clumps. It develops as a well-branched perennial with semi-woody stems at the base and semi-evergreen foliage that keeps a neat outline through much of the year. Flowering runs from June to September, giving a long display of the typical two-lipped blooms. Plant in a sunny, sheltered spot with light, fertile, free-draining loam or sandy soil and a neutral to alkaline pH. A south or west-facing aspect reduces exposure to prevailing winds and helps the plant ripen wood before winter. Good drainage is essential: the main losses recorded come from winter wet rather than cold, so avoid heavy, waterlogged ground and consider an elevated bed or grit-amended soil where winters are damp. Hardiness is H3–H5, which translates to borderline to hardy in UK terms; in the coldest, exposed sites give extra winter protection. Use Penstemon 'Rubicunda' towards the front or middle of a sunny mixed border, in gravel or well-drained rock garden areas, or where a sheltered, warm microclimate can be achieved. Keep the base clear of competing perennial crowns and note that preventing winter waterlogging is the single most effective step to reduce losses.

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 'Rubicunda' 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

Care notes

Pruning and caring for Penstemon 'Rubicunda'

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 'Rubicunda'?

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 'Rubicunda'?

Penstemon 'Rubicunda' prefers full sun. It suits sheltered positions.

What soil does Penstemon 'Rubicunda' need?

Penstemon 'Rubicunda' 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 'Rubicunda'?

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 'Rubicunda' hardy in the UK?

Penstemon 'Rubicunda' 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 'Rubicunda'?

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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