Growing Penstemon

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.

New Penstemon Offerings

As a certified "penstemaniac," I'm always looking to add new species and varieties to our High Country Gardens selection. Here are three new/returning favorites for spring.

• Penstemon pinifolius - New. A little known, but outstanding species native to southwestern New Mexico and southeastern Arizona, pineleaf penstemon is my favorite of all the Beardtongues. The plants are long-lived, have fine-textured, pine needle-like evergreen foliage and bloom in late spring/early summer with a profuse display of orange-red tubular flowers. All of the pineleaf penstemons are more adaptable when it comes to soil; as long as the planting site drains quickly, they will grow well in loamy soils. With hundreds of tubular flowers, the hummingbirds love this species.

• Penstemon pinifolius ' Mersea Yellow' - A returning favorite. An English cultivar, it was selected for its pure yellow flowers and has it back to the US where we can use it as an excellent choice for the xeriscape (waterwise garden) or rock garden. A tidy grower, it's a great choice for edging flowerbeds and pathways where it looks good year-round. 'Mersea Yellow' is a fabulous companion for English lavender.

• Penstemon heterophyllus 'Electric Blue' - New. Known as the Foothills beardtongue, this California native is unrivaled for its intensely blue flowers. This is a species that demands Spartan growing conditions; a gravelly/sandy soil is mandatory. Placement on a slope or raised bed is ideal. Careful watering once established (after about 8-10 weeks) is also important. Don't put it on a drip system as 'Electric Blue' hates consistently moist soil. Adapted to a Mediterranean climate (rain/snow from late fall into mid-spring and almost no summer rain), it really needs very little supplement watering once it reaches the start of its second growing season and beyond. Plant it with Sundancer Daisy (Hymenoxys), Fame Flower (Phemeranthus) and cold hardy Cacti.
• Penstemon pinifolius 'Compactum'' - This is an outstanding form of Pineleaf beardtongue that has a more compact growth habit and smaller mature size than is typical. It blooms in late spring with a profuse display of scarlet-red flowers.

Text by founder and chief horticulturist David Salman.

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© All articles are copyrighted by High Country Gardens. Republication is prohibited without permission.