Rocky Mountain Penstemon (Penstemon strictus)

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Botanical name: Penstemon strictus • Bloom season: Late spring to summer • Bloom color: Deep blue-purple •. Pollinator value: Deep blue tubes worked heavily by bumble bees

Dense spikes of deep blue-purple bells on upright stems; this is a reliable penstemon for a gardener who has not grown them before. It is longer-lived and more tolerant of ordinary garden conditions than the desert species, and bumblebees work it heavily through late spring and summer. It serves as a unique drought-tolerant ground cover even through the winter, when the leaves flatten at ground level and sometimes turn purple, triggered by cold temperatures. Fascinatingly, these same leaves transition back to green and don’t die.

Another special trait beyond the large number of native bees it attracts is the beneficial insects that also prefer its blooms. Plant near your vegetable garden to enlist an army of predators to find pests.

Botanical name: Penstemon strictus • Bloom season: Late spring to summer • Bloom color: Deep blue-purple •. Pollinator value: Deep blue tubes worked heavily by bumble bees

Dense spikes of deep blue-purple bells on upright stems; this is a reliable penstemon for a gardener who has not grown them before. It is longer-lived and more tolerant of ordinary garden conditions than the desert species, and bumblebees work it heavily through late spring and summer. It serves as a unique drought-tolerant ground cover even through the winter, when the leaves flatten at ground level and sometimes turn purple, triggered by cold temperatures. Fascinatingly, these same leaves transition back to green and don’t die.

Another special trait beyond the large number of native bees it attracts is the beneficial insects that also prefer its blooms. Plant near your vegetable garden to enlist an army of predators to find pests.

Size:

Plant Characteristics

Botanical Name: Penstemon strictus

Common Name: Rocky Mountain Penstemon

Native: Native

Native Region: Southern Rocky Mountains; Colorado Plateau

Sun: Full Sun

Water: Low

Bloom Time: Late spring to summer

Bloom Color: Deep blue-purple

Pollinators: Bees; Hummingbirds

Deer Resistant: Yes

Mature Size: W 12"-18" x H 18"-30"

Soil: Sharply drained; lean soil

Pollinator Value: Deep blue tubes worked heavily by bumble bees

Plant Type: Herbaceous perennial

USDA Zones: 3 to 8

Spread Habit: Clumping; self-sows

Available As: Live plant

Growing Notes

Full sun and lean, sharply drained soil. It is the most forgiving penstemon here, but forgiving is relative: it still wants far less water than a conventional perennial and it still dies in waterlogged winter ground. Space about 15 inches apart. Do not amend the planting hole.

  • Water: Low

  • Sun: Full or Partial Sun

  • Soil: Sharply drained; lean soil

  • Mature size: 18 to 30 in by 12 to 18 in

Maintenance

Leave stems standing through winter and cut back in late spring, keeping about a third for insects. Deadheading some of the spikes prolongs the bloom, but leave a few to set seed so the planting renews itself. No fertilizer and no summer irrigation once established. Divide only if the clump falls open, which is uncommon.