Isle alumroot (Heuchera maxima), a native of California’s Channel Islands and a shade-loving member of the Heuchera genus, is an appealing yet hardy underplanting companion for California’s native oaks and other big canopy trees.

Majestic oaks are icons of the native California landscape, however I often wonder how to use them in the garden. Lawns and other highly watered ground covers near the tree’s base are off limits, and while oak leaves and acorns blanket the ground in a naturally beautiful way, the designed landscape sometimes calls for longer.

Island alumroot’s lush yet understated, large-lobed leaves covers the earth yearlong, composed an explosion of petite bell-shaped blossoms in late winter and early spring for a harbinger of spring’s rewards.

Botanical name: Heuchera maxima
Common names: Island alumroot, giant alumroot, island coral bells, Jill-of-the-rocks
Origin: Native to the Channel Islands (off the coast of Southern California)
USDA Islands: 8 to 11; rugged to 12 degrees Fahrenheit (find your zone)
Water necessity: Low
moderate requirement: Light to full shade; coastal sun
Mature dimensions: 1 to 2 ft tall; propagates 3 to 4 ft broad; 1- to 3-foot floral spikes endeavor over foliage
Benefits and tolerances: Flowers attract hummingbirds; drought, shade and deer tolerant
Seasonal interest: Attractive evergreen foliage; spikes of pink flowers during late winter to spring
When to plant: Divide clumps in spring or fall.

Distinguishing traits. Maxima is one of the greatest in the Heucheragenus. While regarded as a native coastal chaparral and scrub, it’s a lush plant. It’s dark to medium bright green foliage that is heart shaped with 3- to 5-inch lobes and that clumps out pretty fast burst. Sometimes the flowers are tinged red. In late winter or early spring, prolific 1- to 3-foot spikes of petite pink blossoms project over the foliage. It’s a pretty unassuming-looking plant that is surprisingly drought tolerant and resilient because of its delicate look. The flowers also look great in cut arrangements.

Photo by Wikimedia commons consumer Toedrifter

The best way to utilize it. Use Heuchera’s shade tolerance and affinity for canyons by underplanting shade trees or siting it into darker garden areas. Maxima is also recognized as a preferred planting beneath native oaks; bamboo leaves make a excellent mulch. Mass it for a lush, soft ground cover or a bedding edge for a cottage garden, spacing plants 2 feet apart. All Heucheras also flourish in mixed containers.

Photo by Stan Shebs

Planting notes. Maxima grows naturally as rocky cliffs and canyons, flourishing in partial to full shade and well-drained humus-rich land. It is more tolerant of clay soil compared to other Heuchera. While it’s a coastal native, prevent direct salt spray. Maxima grows vigorously, through clumping, and is drought tolerant (prevent considerably extra summertime). Split it every three to four decades and deadhead spent flowers.

Photo by Stan Shebs

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