Winter’s Cheerleader, Yelling for Spring - New York Times Annotated

In the Garden

I first encountered Hamamelis mollis, the Chinese species, years ago, at Clark Botanic Garden, in Albertson, N.Y. It was a sunny January day, and this sprawling beauty — 5 feet tall and 20 feet across — lounged like a big blonde sunning in the 12-acre garden.

Unfurling with the sun, the little clusters of clear yellow crimped flowers were sending their sweet scent my way in an impossible promise of spring.

How could these plants be blooming in the middle of winter? And why would they want to?

“It has to do with chilling requirements,” said Peter Del Tredici, a lecturer at Harvard and former director of living collections at the Arnold Arboretum of Harvard University in Boston. The very first witch hazel to bloom, for example, is Hamamelis vernalis, native to the Ozarks, and hardy to 30 below zero. It bloomed in Boston in mid-January.

“Vernalis only requires a month’s worth of chilling,” Mr. Del Tredici said. “That’s long enough for this species. The days are getting longer. And it takes advantage of insects that hatch with the first warm weather.”

The witch hazels that enchant this time of year are H. mollis, the Chinese species; its many cultivars; and hybrids of the Chinese and the Japanese species (H. japonica), which range in color from pale yellow to gold, orange and red.