If all of Seattle can read one book, all of the PNW could grow this shrub

THIS YEAR, I’M reprising a botanical garden party theme that I introduced back in 2021. Inspired by the popular Seattle Reads, a “one book, one city” program offered through the public library, The Seattle Times’ Grow asks: If everyone in our region could grow the same plant, what should it be?

For this year’s twist, I’m reaching out to a local garden pro who knows a thing or two about designing fabulous landscapes for the Pacific Northwest’s moderate but unique growing conditions.

Landscape designer and artist Jil Stenn (stenndesign.com) brings a painterly eye to planting designs. All of the designer’s work is grounded in a deep understanding of plants that she’s garnered from years of “hands-in-the-soil” experience. According to Stenn, Mahonia x media ‘Arthur Menzies’ “surprises and delights with bright yellow panicles of flowers in winter, followed by an abundance of purple clusters of berries in the fall.” The plant is a Great Plant Picks (GPP) selection, so we know it’s a winner in Pacific Northwest gardens.

Visit the Joseph A. Witt Winter Garden at Washington Park Arboretum this month, and look for the large stand of mahonia at the north end of the garden. You can’t miss the golden blossoms glowing in the weak winter light. Even before you see them, you’ll hear the characteristic clicking and whirring of overwintering Anna’s hummingbirds nectaring on the flowers — the rich yellow flowers combined with flashes of the hot pink and lime green tiny birds are a glorious seasonal wonder worth catching on a leaden day in January.

Stenn values ‘Arthur Menzies’ mahonia for its “year-round structure and framework, which is especially useful where height is desired in a narrow space.” The designer also uses the plant where she wants a dramatic foliage backdrop or an evergreen foil to set off seasonal plants the rest of the year.

The statuesque mahonia, a chance garden hybrid of two Chinese species, has literal and historical roots in the Northwest. ‘Arthur Menzies’ originated at Washington Park Arboretum and was named by then-curator Brian Mulligan for his colleague Arthur Menzies of Strybing Arboretum in San Francisco. The selection was made from a batch of Mahonia lomariifolia seedlings, a frost-tender species that Menzies had shared with Mulligan. The hardy hybrid emerged after a harsh winter in 1962 laid waste to the rest of the seedlings, and it has become a majestic presence in winter gardens throughout our region and beyond.

The GPP website describes Mahonia x media ‘Arthur Menzies’ as a vase-shaped evergreen shrub that grows 8 feet tall and 5 feet wide. Inky-green fronds of toothy foliage appear in whorls around multiple coarse trunks. Crowning sprays of yellow flowers in winter, followed by generous crops of waxy purple-blue berries in late summer and into fall, make this plant wildlife friendly and a dramatic, deer-resistant (!) focal point in the landscape.

A beautiful plant with a “tough” constitution, ‘Arthur Menzies’ mahonia thrives in full sun to dappled shade. It prefers well-drained soil but will tolerate sandy sites and clay as well. Drought-tolerant once established, mature plants sited in full sun benefit from occasional watering in especially dry summers. Other hybrid mahonia with similar features to ‘Arthur Menzies’ on the GPP list include ‘Charity’ and ‘Winter Sun’.