The Case for and against Japanese Anemones

Though they are known as "Japanese" Anemones, this common name is actually a bit of a misnomer.

Sometime in the distant past, anemones were brought from their native China to Japan, where they naturalized in the wild. There the fall-blooming plants were discovered by European plant collectors and were mistakenly identified as a Japanese native.

Japanese Anemones in a private garden.

Windflower is another common name for Japanese Anemones and speaks to the delicate flowers that float and dance in the breeze on tall, slender stems. The flowers are two to three inches in size and come in single, semi-double and double forms. Colors range from pure white to pink, lavender and purple.

The plants themselves are long-lived and relatively low maintenance. Division is rarely needed.

They range in height from 2'-4' (60 cm -120 cm).

Anemone x hybrida 'Whirlwind'

Anemone x hybrida 'Whirlwind' at the Toronto Botanical Garden.

One of the great assets of these plants is their bloom time. They begin to flower in mid-to-late August and continue to do so until the first frosts. As you can see in the picture above, the leaves on the trees have all turned color and the Japanese Anemones are still going strong.

Japanese Anemones at the Toronto Botanical Garden.

The downside is that Japanese Anemones are perennials that have a spreading habit. Many would even deem them to be invasive. It may take a year or two for a Japanese Anemone to get established. Given favourable conditions, it will then begin to spread via creeping rhizomes. Eventually, it will naturalize to form a large colony. How fast they spread is somewhat determined by the soil. In heavier, drier soil they will spread more slowly.

The roots of a Japanese Anemone are fairly shallow and fibrous, so it is possible to remove them. Root segments can re-sprout, so it is important to get as much of the roots as possible.

Where you plant them is key to perennials like this. Don't plant them in amongst other less vigorous plants and expect them to be good neighbours.  I'd also be cautious about planting them in an open area where it would be difficult to contain them.

Last weekend I visited a garden where she had her anemones planted in a raised island bed. It struck me as a perfect spot for them. There was only so far they could go.

Anemone x hybrida 'Whirlwind'

How to Grow Japanese Anemones

It is very tempting to buy Japanese Anemones now when you can see the flower in bloom, but it is much better to plant them in the spring when they have more time to get established before winter (particularly in more northern zones).

Plant tags will often describe light requirements for fall-blooming anemones as "full sun" or "part shade". This shorthand really doesn't provide enough information. Light to medium shade that includes a bit of early morning sun is best. If the soil is moist however, Japanese Anemones will tolerate more sun (the exception would be in warmer zones, where protection from the hot afternoon sun is essential). Too much shade will result in leggy plants that flop.  

Japanese Anemones like humus-rich soil that is evenly moist, but well-drained (These aren't bog plants. They prefer regular water that drains away).

Mulch a Japanese Anemone in that first year.  It will help keep the soil moist.

In zones 5 and lower, anemones are best planted in a sheltered location near a building or against a fence. It is also recommended to mulch a Japanese Anemone each fall in more northern area to protect the plant through the winter.

I have read differing views on staking these tall plants. Part of their charm is those tall swaying flower stems. You can reduce the plant's height by cutting it back in the first part of June. Flopping stems can also be a sign of too little light.

Fertilize them in spring. Division is also best done in the spring.

Pests

Japanese beetles and black blister beetles can defoliate an entire plant. The plant may bounce back, but it will be unlikely to flower that season.

Japanese Anemones are deer and rabbit resistant.

Japanese Anemone, Anemone x hybrid 'Party Dress' 

A Few of the Cultivars Available

Anemone tomentosa is native to northern China is the hardiest and most vigorous (i.e. it spreads aggressively) of the fall flowering anemones.

Most modern cultivars are attributed to Anemone hupehensis and Anemone x hybrida.

Anemone hupehensis is native to central and southwestern China where it can be found on grassy slopes and on stream banks. Modern cultivars related to species forms of Anemone hupehensis offer semi-double flowers.

Anemone x hybrida are generally referred to as Japanese hybrids and are a cross between a Himalayan species (A. vitifolia) and Anemone hupehensis.

Anemone tomentosa 'Robustissima' has large, pink flowers on tall branching stems that become fluffy seed heads in the late fall. This is one of the hardiest and most vigorous cultivars. It has an aggressive, spreading habit that many would deem invasive. Like all anemones, it likes moist, rich soil. Part shade. Height: 90-120 cm (35-47 inches), Spread: 60-90 cm (23-35 inches). USDA zones: 3-9.

Anemone hupehensis 'Pretty Lady Emily' has large double flowers that are light pink on a shorter plant.  Like all anemones, it likes moist, rich soil. Part shade. Height: 30-40 cm (12-16 inches), Spread: 50-60 cm (20-23 inches). USDA zones: 5-9.

Anemone hupehensis japonica 'Pamina' has semi-double flowers that are dark pink. Like all anemones, it likes moist, rich soil. Part shade. Height: 80-85 cm (31-33 inches), Spread: 60-90 cm (23-35 inches). USDA zones: 5-9.

Anemone x hybrida 'Party Dress' has a green eye at the centre of large semi-double flowers that are pink. Like all anemones, it likes moist, rich soil. Part shade. Height: 80-90 cm (31-35 inches), Spread: 60-90 cm (23-35 inches). USDA zones: 5-9.

Anemone x hybrida 'Queen Charlotte' has semi-double flowers that are pink. Like all anemones, it likes moist, rich soil. Part shade. Height: 80-90 cm (31-35 inches), Spread: 60-90 cm (23-35 inches). USDA zones: 5-9.

Anemone x hybrida 'Honorine Jobert' is an heirloom variety that plant breeder M. Jobert named for his daughter in France in1858. It has a single white flower with a flush of pink on the outside.  Like all anemones, it likes moist, rich soil. Part shade. Height: 90-120 cm (35-47 inches), Spread: 60-90 cm (23-35 inches). USDA zones: 5-9.

Anemone x hybrida 'Whirwind' is another heirloom cultivar. It has semi-double white flowers on tall stems. Like all anemones, it likes moist, rich soil. Part shade. Height: 90-120 cm (35-47 inches), Spread: 60-90 cm (23-35 inches). USDA zones: 5-9.

Just when summer-flowering plants are finishing, Japanese Anemones step in to fill the void. They usher in the change of seasons with a beautiful profusion of flowers. If you can find a good place for them, they have lots to offer.

Update: Proven Winner's has introduced a new cultivar that is purported to be less aggressive. 

Fall in Love™ Sweetly Japanese Anemone hybrid has semi-double, rose-pink flowers. For most of the summer, the foliage is a large mound of dark green leaves. In late summer/fall, flowering stems make the plant's growth more upright. Unlike most Japanese Anemones, this new introduction spreads slowly through rhizomes. Average, moist soil will keep this plant happy. Mulch heavily in the fall for the first two seasons to prevent frost heaving. Part-sun to full sun. Resists deer and rabbits. Height: 24 - 30 inches (60 -76 cm), Spread: 20 - 22 inches (50-55 cm). USDA zones: 4-8.