Know thy anemone
A classic botanical misnomer, Japanese anemones aren't really Japanese at all—in fact, they were developed about 125 years ago by nurserymen in England, France and Germany, who used several Chinese species (Anemone vitifolia and A. hupehensis var. japonica) to create what we now know as A. x hybrida—an entirely man-made plant, despite its simple, unaffected appearance. Although these plants may not be found in nature—but are extensively found in nurseries and garden centres—they certainly deserve a spot in every garden. These cultivars are only reliably hardy to Zone 6, although they can be successfully overwintered to Zone 4 if well mulched with a 10- to 12-centimetre layer of shredded leaves in fall.
The only truly hardy Japanese anemone is A. tomentosa ‘Robustissima' (hailing from the mountains of Tibet and western China), which is reliable to Zone 4 or, again, when heavily mulched, to Zone 3.
Most of the Japanese anemones that we grow today are more than 100 years old—I like to think of them as living antiques—and the paucity of new introductions is likely because it's hard to improve upon perfection. Nevertheless, cultivars with larger flowers in deeper shades of purple are currently being developed for the cut flower market, although their garden worthiness has yet to be established.