Penstemon (beardtongue) Penstemon digitalis
Penstemon (beardtongue) (Penstemon digitalis) is an evergreen perennial flowering plant in the Plantaginaceae family, native to Eastern and central North America. It grows 60 cm–1.2 m (24 in–3.9 ft) tall and 40–60 cm (16–24 in) wide, wants full sun and moderate water, and is hardy to about -34 °C (-29 °F). Space plants about 45 cm (18 in) apart.
Plan Penstemon (beardtongue) in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Penstemon (beardtongue) at a glance
| Type | Perennial flowering plant, evergreen |
|---|---|
| Family | Plantaginaceae |
| Mature height | 60 cm–1.2 m (24 in–3.9 ft) |
| Mature spread | 40–60 cm (16–24 in) |
| Spacing | 45 cm (18 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Moderate; drought tolerance moderate, waterlogging tolerance low |
| Soil pH | 5.5–7.5 |
| Cold hardiness | About -34 °C (-29 °F) once established (roughly USDA zone 4) |
| Heat stress | Likely above about 33 °C (91 °F) |
| Flowering | from about May for 3–5 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | High |
| Edible | Not grown as food |
| Native to | Eastern and central North America |
| Common in gardens of | 🇺🇸 United States, 🇬🇧 United Kingdom |
Is Penstemon (beardtongue) toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
Not listed as toxic by ASPCA or standard poison references for Penstemon digitalis.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Penstemon (beardtongue)
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
See Penstemon (beardtongue) in a botanical garden
It grows in these sample gardens, which you can walk through in 3D:
- Arctic-Alpine Botanic Garden (12 plants)
- Denver Botanic Gardens (30 plants)
Questions about Penstemon (beardtongue)
- How far apart should I plant Penstemon (beardtongue)?
- About 45 cm (18 in) apart, centre to centre. A mature plant spreads 40–60 cm (16–24 in).
- Does Penstemon (beardtongue) need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Penstemon (beardtongue) need?
- Moderate water. Drought tolerance is moderate and waterlogging tolerance low.
- How cold-hardy is Penstemon (beardtongue)?
- It tolerates about -34 °C (-29 °F) once established, roughly USDA zone 4.
- When does Penstemon (beardtongue) flower?
- From about May for 3–5 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Penstemon (beardtongue) poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. Not listed as toxic by ASPCA or standard poison references for Penstemon digitalis.
- What grows well with Penstemon (beardtongue)?
- There is no well-documented companion pairing for Penstemon (beardtongue). Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
- Extension Gardener Plant Toolbox, NC State Extension
- RHS Plant Finder, Royal Horticultural Society
Notes and assumptions
- Typical garden-form values; cultivars and local conditions differ.
- Semi-evergreen basal rosette; tolerates moist soil better than most western penstemons.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Foxglove Digitalis purpurea
- Snapdragon Antirrhinum majus
- Hebe Veronica speciosa
- Fairy foxglove Erinus alpinus
- Parry's penstemon Penstemon parryi
- Rice paddy herb (ngò om) Limnophila aromatica
- Angelonia (summer snapdragon) Angelonia angustifolia
- Spiked speedwell Veronica spicata