PLANT OF THE WEEK #109: Penstemon 'Catherine de la Mare'

Penstemon ‘Catherine de la Mare’, a cultivar of Penstemon heterophyllus, doesn’t come from France, let alone the ocean. Yet the grandiose name doesn’t betray any lack of class. This North American beauty embodies understated elegance fitting for the occasion; on cooler days, blooms appear in deep blue hues, while warmer temperatures soften the flowers to a gentle lavender. The combined effect evokes the colours of the sea (la Mare). 

Penstemon ‘Catherine de la Mare’ arrives in the intermission between spring and summer – a time that provides pause for its worthy reflection. The slender, upright stems form a tidy structure that stands about gumboot-high, topped with clusters of tubular flowers that draw in pollinators, adding a refined, vertical aspect to the front of a border. Catherine thrives in well-draining sandy or loamy soils with a neutral to slightly acidic pH. While suitable for full sun to partial shade, more intense blooms emerge under brighter light conditions.

As a novice gardener (thank you to Michael for indulging my desire to contribute this post), my initial enthusiasm for penstemons, particularly ‘Midnight’ and ‘Sour Grapes’, reflected my excitement that I could grow anything at all. With a few seasons under my belt, I began to resent their lack of movement, a quality admonished by any self-respecting gardener. Indeed, with meadow-style gardens becoming de rigueur, Catherine might be at risk of becoming old-fashioned. But for gardeners like me, who lack the technical skill to mimic uncontrived naturalism, Catherine de la Mare can add structure to a mixed border or soft charm to a more traditional cottage garden design.

Regarding care and maintenance, Catherine is both generous and undemanding. As a beginner, I watered everything as much as I would plants in captivity (aka pot plants), soon learning that Catherine thrives when soil is allowed to dry out between waterings. Moderation is key, as too much moisture invited Botrytis (grey mould), a fungal pathogen that thrives in damp conditions. This was a lesson in restraint, proving that even the hardiest plants appreciate a balanced hand. In terms of pruning, deadheading spent blooms will encourage a longer flowering season, while a light trim in late winter can promote lusher growth, all but guaranteeing Catherine’s enduring dignity.

Joel is a self-proclaimed ‘novice gardener’ from Lyonville, Victoria, and client of Simon Rickard.