. It goes hand in hand with polar bears dying in the Arctic as the sea ice shrinks.

In central Maryland, warmer winters allow me to grow Southern magnolias and apricot trees, but more insects are wintering over, and weeds, like poison ivy and ragweed, seem far more aggressive. It didn’t surprise me to see that my garden has jumped a zone, from 7 to 8, according to a hardiness zone map based on lowest winter temperatures in the past 15 years, just published by the National Arbor Day Foundation (

The Agriculture Department’s Research Service is also revising its hardiness zone map, based on temperatures over the past 30 years, so stay tuned.

, said that winter temperatures in the Northeast have increased an average of 4.3 degrees over the last 30 years.

That may not seem like very much, Mr. Wake said. But picture Boston experiencing a winter climate more like Philadelphia’s; or Philadelphia having winters more typical of Washington.

All kinds of plants are changing their patterns. According to research by David W. Wolfe, a professor of horticulture at

, lilacs are blooming an average of four days earlier than they were in the 1960s; apple trees and grapevines are blooming about eight days earlier.

That can have a downside. Earlier spring warming does not rule out sudden drops in temperature. If the trees are blooming earlier and there is a cold spell, there is a risk of frost damage to flowers and to developing fruit.

Apple trees need a winter chilling period of at least 30 consecutive days with temperatures below 40 degrees, Mr. Wolfe said. And winter thaws that interrupt that chilling period inhibit fruit production.

As the warming trend continues, gardeners and farmers are changing the varieties of vegetables and fruits that they grow.

Prudence Wickham Heston, a partner in Wickham’s Fruit Farm in Cutchogue, N.Y., described crops that once would not have survived on the farm. Her family is growing peach and apricot trees down near the Peconic Bay, which holds warmth in the fall and stays cool in the spring, producing ideal conditions for these crops. They have also planted kiwi vines, which would have been unheard of in Grandfather John Wickham’s day, when people used to drive across the frozen bay to Southampton.

But Tom Wickham, Ms. Heston’s uncle, worries that the mild winters will bring more insects and disease.

“Apple scab will over-winter in dead leaves and twigs, but a really cold winter, of about zero degrees, will suppress it,” Mr. Wickham said. “We used to have winters well below zero, but we haven’t had that for a long time.”

Warmer temperatures have also benefited Long Island’s grape growers, who are starting to plant syrahs, which need more heat to develop flavor, said Louisa Thomas Hargrave, a former vintner who is the director of the Center for Wine, Food and Culture at

“When Gloria hit in 1985, it came loaded with spray from the sea, and all that salt was deposited on the leaves,” said Charles Massoud, who with his wife, Ursula, owns Paumanok, a 75-acre vineyard in Aquebogue, N.Y. Luckily, the Massouds were able to harvest their grapes the day before the storm struck, on Sept. 27.

As for the weeds in our lives, they are growing bigger and faster, and producing more seeds, as temperatures rise.

“Japanese honeysuckle and English ivy seem to be responding very well to CO2 and warmer temperatures,” said Lewis Ziska, a weed scientist based at the Agriculture Department’s office in Beltsville, Md.

And they are more resistant to herbicides, he said. Canada thistle, for example, grown in a chamber of elevated carbon dioxide, was not killed until sprayed with three times the regular dose of herbicide.

And each ragweed plant “can produce 10 times the amount of pollen, just because of climate change and CO2,” he said, making the pollen counts much higher.

Obviously, we can have some fun pushing the envelope. But on the more serious side, we need to be setting rain barrels under our roofs to harvest the increasing number of torrential downpours.

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