Penstemon cardwellii (Cardwell's Penstemon)

Cardwell's Penstemon (Penstemon cardwellii) is a true Cascade subshrub of Oregon and Washington, hugging open rocky ridges, recent burn scars, and lava-bench openings from Mt Hood south through Crater Lake and into the Klamath country. Glossy evergreen leaves cover a low woody framework that mounds eight to sixteen inches tall and slowly spreads outward by layering, eventually two to two-and-a-half feet across.

From late May into July the whole plant turns blue-violet to royal purple as tubular two-lipped flowers open in dense clusters along upturned stems. Bumblebees push deep into the throat for nectar and pollen, and hummingbirds work the flowers for the same nectar reward. Once the bloom is finished, slim seed capsules ripen quietly into late summer.

Cardwell's Penstemon asks for the conditions it grew up with on volcanic ridges. Sharp drainage above all else. Full sun to a little afternoon shade. Lean rocky soil. Low summer water once established, and absolutely no winter wet, which is the single most common cause of mid-garden failure with Cascade penstemons. A south-facing slope, a rock garden, a gravel-mulched trough, or the top of a dry stone wall are all happy homes. USDA Zone 5 to 8.

This is a Cascade species, not a coastal one. Inland from the immediate shore, salt spray and ocean fog are not its element. Deer routinely walk past Penstemons because of bitter iridoid compounds in the foliage.

Pairs naturally with Eriogonum umbellatum, Sedum oreganum, Phlox diffusa, Aquilegia formosa, and the dwarf native bunchgrasses for an honest Cascade ridgeline meadow.