Posted by Aaron Barton on Mar 4th 2023
Actaea (Bugbane/Black Cohosh)
Often overlooked, the humble late summer shade garden provides some of the most beautiful late season color, with many of its best and boldest bloomers just beginning their late season show on the doorstep of fall. One of the best shady accents, Actaea simplex (ak-TEE-uh SIM-plecks), also known as bugbane or black cohosh, was temporarily reclassified as Cimicifuga simplex before recent findings confirmed Carl Linnaeus’ original assertion made in 1753, renaming the species to Actaea simplex once again. Belonging to the buttercup family, Ranunculaceae, the many dark-leaved bugbane cultivars are also often referred to as the Atropurpurea, or “dark purple” group of A. simplex.
Native to northeastern Russia, China, Mongolia, Korea, and Japan, not to be confused with the green-leaved North American native Actaea racemosa, bugbane is a part sun and shade loving perennial, thriving in consistently moist, well-drained soils, unbothered by deer or rabbit feeding. Though tolerant of even deep shade, blooms are most abundant in part shade conditions, performing well with morning sun and afternoon shade.
Named black cohosh in reference to the Algonquin word for “rough,” Actaea produce rough, large darkly colored rhizomes from which the plant emerges in the spring, gently spreading by rhizomes to form a lush clump in favorable conditions. Actaea develop mounds of lush, deep green or purple foliage, with trifoliate deeply cut compound leaves on dark petioles, forming a dramatic mound of foliage around two feet tall and wide, providing great contrast and foliage interest throughout the season.
In the late summer and fall, black cohosh steals the show, producing numerous massive blooming stems with one to three terminal racemes of elegant bottlebrush white blooms towering up to six feet tall, almost appearing pearl-like before opening from the bottom upward with a wonderful jasmine vanilla fragrance. Serving as a great source of late-season nectar for pollinators, Actaea is perfect for woodland gardens, tall shady backdrops, or even cottage gardens. Popular cultivars include ‘Black Negligee,’ with emerald green foliage developing into a rich dark purple color, ‘Chocoholic,’ with deep purple foliage and pink-tinged blooms, and ‘Brunette,’ a slightly more compact selection with beautiful bronze foliage and bright white blooms.