Great Design Plant: Large Beardtongue (Penstemon grandiflorus) — Spring-to-Summer Bridge for Dry Gardens

Large beardtongue (Penstemon grandiflorus), or shell-leaf penstemon, is the grandest of its genus. Big blooms and blue-gray foliage bring a cooling presence just as summer heat arrives. It's a bridge plant—echoing spring ephemerals in flower, yet tough and drought-tolerant for high summer. If you have dry, gravelly, or sandy soil, you've found your dream perennial.

Sierra Rain Shadow

Plant Profile

• Botanical name: Penstemon grandiflorus
• Common names: Shell-leaf penstemon, large-leaf beardtongue, showy beardtongue, large penstemon, large beardtongue, large-flower beardtongue, large-flower penstemon
• Origin: Texas and New Mexico north to Montana, east through Wisconsin, Missouri, Indiana, Michigan
• Hardiness: -40°F, USDA zones 3–8
• Water: Medium to dry soil
• Light: Full sun
• Mature size: 2–3 feet tall, 1 foot wide
• Benefits: Very drought-tolerant; excellent hummingbird plant
• Seasonal interest: Late spring to early/mid-summer bloom; smooth blue-gray foliage
• Planting time: Potted/bare-root: late spring to late fall; seeds: late fall through winter

Benjamin Vogt / Monarch Gardens

Distinguishing Traits

Largest blooms in the genus—~2 inches long. Hummingbirds love them; diverse bees crawl deep into the spacious throats. Flowers last just a few days (blooming bottom-to-top), but the smooth, blue-gray leaves provide lasting cool-toned texture. Bloom: May–July depending on latitude.

Photo by Aaron Carlson

Landscape Uses

Best in small groups given its airy, open stems. Works in traditional borders or prairie-style gardens. Contrast its broad leaves with fine-textured grasses or coreopsis. In rich soil, stems may reach 4 feet but become inconspicuous post-bloom—plan a midsummer successor to fill the gap.

Planting Notes

Rare in the wild due to habitat loss and need for sharp drainage. Most common on sandy sites; tolerates well-drained clay or gravel. Moisture causes root rot. Plant on slopes, elevated spots, or raised beds. Loves heat and sun, thrives on little rain.

Photo by Andrey Zharkikh