HARDINESS: Zones 5 to 8
PREFERRED SOIL pH: Near neutral
PREFERRED SOIL TYPE: Fertile, moist soil
PREFERRED LIGHT: Partial shade
ATTRIBUTES White or pink flowers, divided green foliage; for beds
SEASON OF INTEREST: Late summer to autumn
FAVORITES: 'Honorine Jobert', 'September Charm', A. tomentosa 'Robustissima'
QUIRKS: Spreads quickly when grown in full sun
GOOD NEIGHBORS: Astilbe, cohosh, hosta, hydrangea, spiraea
WHERE IT GROWS BEST: Fertile, moist soil in partial shade
POTENTIAL PROBLEMS: Winter damage in areas colder than Zone 5
RENEWING PLANTS: Lives many years; divide clumps in spring and replant immediately
CRITTER RESISTANCE: Good except for deer and Japanese beetles
SOURCE: Bedding plants, division
DIMENSIONS: 2-4 ft (0.6-1.2 m) tall, 1-3 ft (0.3-1 m) wide
Japanese Anemone in the Landscape
Among the last perennials to bloom, Japanese anemones finish the season with style. The 2 in (5.1 cm) wide, open-faced, soft pink to white flowers are held high above divided green leaves and appear well into fall. Combine them with hostas and the compact, golden-leaved 'Gold Mound' spiraea. Or grow them in masses where they can spread without bothering their neighbors.
The Tall, the Short, and the Hardy
Most Japanese anemones offered for sale are Anemone x hybrida. Among the taller cultivars are the single-flowered 'Honorine Jobert' and semi-double 'Whirlwind', both with white blooms that reach 4 ft (1.2 m) tall. 'Queen Charlotte' is another tall type, with semi-double rose pink flowers.
Dwarf Japanese anemones (A. hupehensis var. japonica) stand only 2-3 ft (0.6-1 m), making them suitable for the front or middle of the border. These include 'September Charm', which has silvery pink single flowers, and 'Bressingham Glow', with vivid rose semi-double blossoms. The most reliable Japanese anemone for Zone 5 gardens is A. tomentosa 'Robusdssima'. True to its name, this is a hardy, pink-flowered cultivar that thrives in cold-winter areas where other Japanese anemones struggle or die.
Planting and Caring for Japanese Anemone
To give Japanese anemones a good start, turn the soil and amend it generously with aged manure or compost before setting out plants in spring. Water them to keep the soil slightly moist, and mulch with chopped leaves or another organic mulch. Be patient, as plants often take a year or two to show vigorous growth. In Zones 5 and 6 add a 4 in (10.2 cm) thick mulch of shredded leaves after the first hard freeze in late fall to help ensure the plants' winter survival.
The more sun Japanese anemones get, the faster they spread. Shade slows this tendency but also diminishes flower production. Experiment with sun exposure in your garden to find the right balance of vigor, strong flowering, and restrained spread.
Plants might require division as often as every 3 years if grown in sun, or as seldom as once a decade if grown in shade. To separate crowded clumps or increase your plantings, dig and cut apart the growing points, or crowns, in early spring, making sure each division has healthy roots and a growing point. Replant at the same depth at which the parent plants grew.
Few pests or diseases plague Japanese anemones, but the exceptions are formidable: deer and Japanese beetles. Tuck bars of deodorant soap among plants to repel deer, or apply commercial repellents per label directions. Japanese beetles are more attracted to plants growing in sun than shade, so site plants in shade to discourage this pest. You can also pick and dispose of the beetles in the morning when they are sluggish, or in spring apply the biological insecticide beneficial nematodes to the soil according to package directions to control their larvae.