Green Thumbs Up: Prepare trees and shrubs for the chilly months ahead
Despite the disappointment of another damp and dreary Saturday, a recent storm has provided beneficial moisture to our lawns and gardens after nearly a two-week reprieve from this season’s consistently soggy scenario.
Scattered frosts, swirling winds and wet weather have undressed many of our trees and shrubs, their silhouettes a stark contrast to those that still display their colorful autumn garb.
The lingering leaves of ornamental pear trees (Pyrus) are particularly showy this season, providing a rainbow of fall colors that glow in the landscape long after the multicolored leaves of our native maples have fluttered to the earth. Willows, often the first to don tender green leaves in spring, are among the last to shed their slender leaves at season’s end, while the foliage of beech and oak often cling to branches until the snow flies.
Several varieties of Spirea continue to don their autumn garb, including S. "Gold Mound" with yellow-tinted foliage and the gracefully arching branches, and S. "Ogon" with persistent delicate leaves of amber and orange. Oakleaf hydrangeas are a personal favorite, displaying elegant burnished bronze leaves on decorative peeling branches coated in orange-brown suede.
I prefer to delay all major pruning of trees until late winter or early spring as fresh cuts sometimes fail to heal properly once freezing temperatures ensue. Storm-damaged branches, however, should be trimmed as soon as they are noticed. Jagged cuts may pose a hazard to healthy tissue during the winter, as they tend to collect water -- potentially leading to disease.
Partially broken tree limbs, if left dangling, may eventually cause the bark of the trunk to be stripped beneath the tear. Take a few minutes to inspect your trees and prune any diseased or injured branches before winter weather arrives.
Light pruning of flowering shrubs may help to reduce winter damage, especially for plants in exposed open areas or under eaves where snow falling from the roof or dripping water and ice pose a hazard.
Tall, vigorous butterfly bushes could be pruned to 3 or 4 feet as they may be uprooted during winter storms. In the spring, these glorious summer bloomers that bloom on "new wood" should be pruned again to a height of 1 to 2 feet to promote dense, compact growth. But since they are susceptible to winter dieback, severe pruning in autumn could lead to their demise.
Similarly, if the canes of hybrid tea or shrub roses are especially long, it is advisable to trim these back to approximately 3 feet in height to lessen the possibility of damage caused by wind or snow. Remove all dead or diseased shoots. Major pruning of rose canes, again due to the potential for winter dieback, should wait until spring when all but the strongest, healthiest canes can be eliminated. Be sure to rake up and dispose of rose foliage to minimize diseases over-wintering in the ground surrounding your plants.
Avoid severe trimming of early spring-blooming shrubs as you will remove many of next year’s flower buds.
Our pink and blue mophead hydrangeas thrived this season in response to our abundant moisture, producing especially tall, vigorous stems, posing a dilemma for gardeners as many of these shrubs outgrew their allotted spaces.
Since older cultivars develop their flower buds on "old wood" near the tips of their stems, major pruning in fall or early spring may eliminate most of next year’s flowers. Given a reasonable winter season, these hydrangeas could be spectacular next summer, so I plan to wait until spring to determine the fate of these overgrown shrubs, perhaps clipping some of the tallest stems but waiting until after bloom to a perform major pruning.
For now, protecting the existing woody stems from winter cold and desiccation is my top priority. To ensure blossoms next season, construction of a burlap windscreen to the top of the stems may be helpful to protect plants growing in exposed areas. Fill the interior space with white pine needles or oak leaves. Anti-desiccant sprays applied to the protruding leaf buds along the stems may also prove helpful.
The new hydrangea introduction "Endless Summer" blooms on both old and new wood, ensuring blooms despite winter chills, but for a longer season of bloom, similar protection could be applied.
Evergreen plants, especially broad-leafed shrubs including rhododendrons, azaleas, mountain laurels, andromedas, boxwoods and hollies, are prone to desiccation from wind and winter sun.
Many of these shrubs have superficial root systems, making them especially vulnerable in cold open winters when the ground freezes deeply and their roots are unable to absorb moisture. Several inches of shredded bark mulch should be maintained over the root balls to assure moisture retention in the months to come, although the mulch should not come into direct contact with woody stems.
Anti-desiccant sprays, such as Wilt-Pruf or Wilt-Stop, are available from your local nursery and can be applied to all evergreen foliages prone to winter burn. Make applications when temperatures are above freezing in late November or early December and again in early February to further protect their leaf surfaces.
November and December are usually very busy months for many garden clubs. Many organizations hold holiday greens sales and boutiques or host spectacular holiday house tours. Fabulous seasonal arrangements and creative decorations offer inspiration and the festive atmosphere will surely promote the holiday spirit while supporting local beautification projects.
Suzanne Mahler is an avid gardener, photographer and lecturer who has been developing the 1.5-acre property surrounding her home in Hanover, Mass., for more than 30 years. She is a member of two local garden clubs, past President of the New England Daylily Society, an overseer for the Massachusetts Horticultural Society and is employed at two garden centers.