Coconino County Penstemon in the garden. Photo by Emmis Oure.

Growing Penstemon

By David Salman, Chief Horticulturist

I've always considered the Penstemon family to be the royalty of our Western wildflowers. Their beauty and regal presence in bloom are unmatched by few other perennials. With over 300 species to choose from, there is a Penstemon (Beardtongue) for every type of planting. From rock garden to large-scale xeriscapes, there are a lot of great choices. Growing Penstemon is straightforward, as they are extremely resilient when well-matched to their planting site, and are excellent naturalizing plants when encouraged to re-seed themselves. For beginners, we recommend growing a few of the easier species like Rocky Mountain Beardtongue (P. strictus), Pineleaf Beardtongue (P. pinifolius) and the beautiful Penstemon 'Elfin Pink'. Last but not least, Penstemon's nectar-rich flowers are indispensable to pollinators like bumblebees and hummingbirds.

Watch: How To Plant Penstemon With David Salman

Planting & Growing Penstemon Successfully

Since many Penstemons are adapted to harsh Western habitats, it is important to keep a few cultural considerations in mind when bringing them into our gardens. The keys to successfully growing Penstemon include:

Planting them into "lean" (infertile) fast-draining soils. Sandy or gravelly soils are ideal. Wet clay soils and Penstemon aren't compatible.
Avoid overly enriched soils; too much compost can shorten their life span.
Plant high, leaving the top of the rootball just above the surrounding soil to avoid burying the crown of the plant.
Use them in new plantings where they can enjoy establishing themselves without a lot of root competition from mature neighboring plants.
Plant in full sun.
Deep, but infrequent watering (once established).
Leave some seeds to ripen on the plants when deadheading. Seedlings from the original plants are always more vigorous and longer-lived than their parents.
Mulch with gravel. This encourages re-seeding and protects the crowns from sitting wet over the winter. Avoid bark, grass clippings, or compost as mulch materials, which can introduce fungal problems and rot the plants.

Growing Penstemon: Garden Care

Penstemon are pioneer plants. They are nature's choice to be among the first plants to colonize disturbed landscapes that result from fire, erosion, and road cuts. These are very nutrient-efficient plants and excessive fertilization (especially with Miracle-Gro or other chemical fertilizers) pushes excessive growth and makes them much less perennial. When growing Penstemon, to keep them healthy and blooming strongly, a once-annual application of a natural/organic fertilizer in the fall with Yum Yum Mix is ideal. No compost or manure; it's too rich.