Kept From Hibernation By a Lingering Warmth
Plants Showing Off Early Have Hidden Strengths To Weather a Deep Freeze (Whenever That Arrives)

By Adrian Higgins
Washington Post Staff Writer
Friday, January 5, 2007

In private gardens and public parks, a freakishly mild winter has brought forth a cornucopia of blossoms, from the camellia bushes to the first of the daffodils. If the region's flora is confused, spare a thought for the dumbfounded homeowner who doesn't know whether to rejoice or worry about global warming and a springtime in shambles.

"Very unusual year and in a way kind of alarming, because who knows what's going to happen next," said Joe Dysart, a retired auditor and rose grower in North Arlington. He was finishing the last of his October chores this week, winterizing the lawn mower and oiling and cleaning the garden tools. "I cut my grass two weeks ago."

Contrast that with the plant lover's usual winter regimen -- huddling indoors, poring over seed catalogues and trying to figure out how to jazz up the yard for the spring and summer.

The advice from horticulturists is don't fret, just enjoy it. If a prolonged freeze should come, the plants in bloom will live to fight another winter, even if their blossoms are zapped. "Whether this is a [warming] trend or a gift, get out there," said Phil Normandy, plant curator at Brookside Gardens in Wheaton.

Not all the winter blooms are that unusual, but in a colder winter, they flower shyly and retreat during hard freezes. This year, the blossoms are full and conspicuous, prompting more people to notice and many to worry that our little slice of paradise has lost the plot.

Two plants in particular may have raised the anxiety level thanks to mistaken identity. Winter jasmine is a tough, mounding shrub that blooms on and off through the winter but looks very much like the March-flowering forsythia. The second is the autumn-flowering variety of Higan cherry, which is confused with the Yoshino cherry trees that bloom in April near the Tidal Basin. Normally, the Higan cherry blooms sporadically through the winter, finishing with a flourish in March. In other words, these yellows and pinks are quite naturally taking a winter bow, even if the curtain calls just keep coming in 2007.

Another cherry relative, precocious by nature and called the Japanese apricot, is also in full bloom this week, several weeks ahead of schedule, Normandy said.

The year's balmy start has also led to some uncommon flowering, but, again, nothing to worry about. Two types of hellebore, a perennial, and, even more oddly, the Japanese flowering quince are showing their colors. And flower lovers will notice healthy displays of an evergreen shrub named mahonia and even a spirea named Mellow Yellow. The fall-blooming camellias have remained in full bloom, Normandy said, and the first of the spring-blooming Japanese camellias are opening. The latter will continue to open in coming weeks and may be damaged by freezes.

Normandy even reports honeybees feasting on the mahonias' fragrant sprays of yellow flowers rather than huddling in their hives.

At Green Spring Gardens Park, in Fairfax County, which maintains a collection of rare witch hazel varieties, horticulturist Brenda Skarphol reports varieties of the vernal and Chinese witch hazels in full array as well as the first blooms of the showy Asian hybrids. Witch hazels normally begin blooming later in the winter.

Some bulbs, too, are flowering. The snowdrops are beginning to show, which is not that unusual, but the Rijnveld's Early Sensation daffodil has outdone itself and began blooming at Brookside shortly after Christmas, Normandy said. The same variety was in flower three weeks earlier in Tidewater Virginia, said Brent Heath, a bulb nurseryman in Gloucester. "The earliest we have had it bloom here," he said. "Typically, it blooms the first of January." He has snowdrops in flower along with various crocus and wind flower.

Will a prolonged plunge on the thermometer destroy these brave blossoms? For some, yes -- Normandy notes that the winter jasmine rarely gets to reach full bloom before the unopened buds are killed by freezes. But other flowers can take frosts. The witch hazels, for example, curl up their straplike petals for protection. Most bulbs, too, can take temperatures down into the teens, even in flower.

And the bulbs in flower represent a fraction of the display of spring-flowering bulbs. The warmth will not affect the major show of daffodils, hyacinths and tulips, which usually begins in mid-March and lasts until the beginning of May.

Bulbs that will bloom in March and April need cold weather to form, and problems only arise when the bulbs are in full growth and then temperatures plummet to near zero. This can cause the foliage to collapse, because the leaves are more tender when fully grown than as shoots emerging from the soil.

Heath, co-founder of Brent and Becky's Bulbs, said that if people are worried about freezes, they can apply a light mulch of pine needles around the foliage. Or follow his tongue-in-cheek advice: "Take your thumb, put it on the top of the foliage and push it back down."

This floral display, Normandy points out, doesn't mean that the garden is going to be spent or destroyed by winter freezes before spring arrives. Many of the mainstays of early spring -- most bulbs and flowering dogwoods, ornamental cherries and crab apples -- are in deep hibernation and far from flowering.

The warm winter has also breathed life into the garden in other ways -- by keeping evergreen ground covers, such as liriope and cranesbill, looking perky, the lawn green and hardy potted plants in bloom, including heaths, snapdragons and violas. Freezes have a way of flattening and dulling ground covers and causing conspicuous shrubs, such as rhododendrons, to wilt badly.

Temperatures in the 50s and 60s also allow die-hard gardeners to get out and work, adding organic matter to their soil, making compost and finishing fall cleaning chores.

The warmth is not all good for gardens. Gail Griffin, superintendent of the garden at Dumbarton Oaks in Georgetown, said the wax scale insect is more likely to survive. So will spores of fungi, so removing diseased leaves of such things as lilacs and even tomato plants is important to reduce problems next season. But in the elaborate rose garden, Griffin and her gardeners cannot get the roses to shut down for the winter. Still in last season's leaf, they are harboring black spot. Dysart reports the same problem in his Arlington garden. Griffin is planning to strip the leaves off the roses.

Winter weeds, too, are growing robustly and need to be pulled, said Skarphol of Green Spring Gardens. She lists chickweed, veronica, bittercress and deadnettle. "And the ground ivy never slows down," she said. "It's just evil."

Then there's the psychological damage. Janet Draper, a horticulturist at the Smithsonian Institution, said: "I actually like this weather, but I know we are going to pay for it. If it's this warm now, what's it going to be like in July and August?"

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