< Back to front page Text size – +

Spring heat, chill prolong flowers' bloom

E-mail|Link|Comments () May 15, 2009 12:59 PM

By Andrew Ryan, Globe Staff

New England's famously fickle weather has oscillated to new extremes this spring: A record high of 93 degrees in late April, followed by lows plunging into the 40s for much of May. The temperature roller coaster, however, has done more than offer false teases of summer.

(RG Mayer/Arnold Arboretum Archives)

The early blast of heat jump-started flower buds, coaxing pink cherry blossoms and lavender-colored lilacs out of dormant branches. The ensuing chill then slowed down the process, prolonging the life of blooming flowers. Think of a refrigerated display case at a florist the next time a cold breeze causes a shiver.

"It's a fortunate year for us," said Julie Warsowe, manager of visitor education at Arnold Arboretum, which overflowed this week with fiery torch azaleas, brilliant white dogwoods, and a spectrum of colors from almost 200 varieties of lilacs. "We get to enjoy them a little longer."

Nuances caused by the temperature swings aren’t necessarily unusual, but the subtleties are evident to researchers such as Sue Pfeiffer, a curatorial fellow at the arboretum helping with a study of microclimates in the 265-acre preserve. A cherry blossom grove near Dawson Pond, for example, began blooming on May 6, almost two weeks earlier than flowers appeared on the same trees last year.

"The heat sped up the buds and got them ready," Pfeiffer said. "Then it got cool and the flowing time extended."

The lilacs, of course, are the main draw most springs at the arboretum. At the start of this week, tens of thousands streamed to Lilac Sunday, an annual rite dating more than 100 years. This year the white, violet, and plum-colored petals were at their peak, preserved in part by the cold. Next comes the flowering of the honeysuckle and dogwoods

"That's the great thing about the arboretum," Warsowe said. "There is always lots of things in bloom."