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perennial

Rocky Mountain penstemon

Penstemon strictus

Preview: plant data is awaiting horticulturist review. A professional horticulturist hasn't reviewed our plant table yet. Lists still follow fixed rules for zone, sun, pets, deer and invasive status.

Penstemon strictus is a semi-evergreen perennial for gardens in zones 4–8. It grows 1.5–2.5 ft tall and 1–1.5 ft wide, so plant it 1.25 ft apart. Give it full sun and little water once established. It flowers blue in May to July. In a FloraVista list it usually plays the filler role: a flowering plant that fills the middle or front of the bed. It is native to the Mountain West and the Desert Southwest. Deer usually leave it alone, and it is not listed as toxic to dogs or cats. Our rules leave it out of lists in the Northeast, the Mid-Atlantic, the Southeast, Florida and the Gulf, Texas and the South-Central states, the Pacific Northwest and the Midwest, where summer heat, humidity or mild winters hold it back even inside its zone range.

Facts from our plant table

Botanical name
Penstemon strictus
Plant type
Perennial, semi evergreen
Hardiness zones
4 to 8
Sun
Full sun (6+ hours)
Water
Low
Soil
Lean, fast-draining soil; rots in clay or with summer irrigation.
Mature size
1.5–2.5 ft tall × 1–1.5 ft wide
Spacing
1.25 ft apart (centre to centre)
Growth rate
Medium
Bloom
May–Jul · blue
Roles in a bed
Filler
Styles
natural, low water
Deer resistance
High: deer rarely eat it
Pets
Not listed as toxic to dogs or cats. Penstemon is not on the ASPCA toxic list.
Native to
Mountain West and Desert Southwest
Pot size and price
1-gallon pot, typically $10–$16 (sometimes stocked)
Plant in
Spring or Fall
First-year watering
Water weekly through the first summer until roots establish, then only during long dry spells.
Pruning
Remove spent stalks; leave the evergreen rosette.

Sources: ASPCA Toxic and Non-Toxic Plant List (from general knowledge; not re-checked unless verification is web-checked); Missouri Botanical Garden Plant Finder and grower tags; State extension service guidance and USDA PLANTS distribution maps; Rutgers NJAES Landscape Plants Rated by Deer Resistance; Invasive Plant Atlas of the United States and state noxious weed lists; Typical 2026 US garden-centre and big-box retail listings (estimate). Not yet reviewed by a horticulturist.

Good companions

The plants our list engine most often puts in the same bed as Rocky Mountain penstemon, across the sun, zone, pet, deer and style combinations it fits.

If you can't find it

Substitutes our engine offers for Rocky Mountain penstemon: same role in the bed, passing the same rules. Some of them are flagged toxic to dogs or cats: check the pet note before you swap.

How this page was made

This page was generated from this plant's record in FloraVista's plant table by fixed rules. The companions and substitutes come from the lists our rules engine composes. No named expert has reviewed this page.

Data status: the plant table is awaiting review by a horticulturist. Check each plant with a local nursery or extension office before you buy.

Sources

  • Missouri Botanical Garden Plant Finder, state extension services and the USDA PLANTS database (zones, size, sun, water, bloom, native range)
  • ASPCA toxic and non-toxic plant lists (dog and cat toxicity)
  • Rutgers NJAES and regional extension deer-resistance ratings
  • State noxious-weed and invasive-plant lists and the Invasive Plant Atlas of the US
  • Typical US garden-centre listings (pot size and price band)

Generated . How FloraVista chooses plants