Protecting Plants for Winter

The weather is already menacing. And it’s bound to get worse. Blustery winds, drifts of snow, and wicked low temperatures are all in our future. There will be trial by ice and ordeal by sleet; four-legged nibblers will roam the earth. You know the drill.

Although you can’t do a thing to change the weather, you can hedge your bets against it and hungry deer, too. A little planning at planting time and some preemptive action before winter sets in can preserve the life and limbs of valuable and beloved shrubs and trees, and forestall a whole bucket of tears.

THE RIGHT LOCATION

Gardening isn’t all about whims and fancies. If you installed that broadleaf evergreen on the south side of a building the better to partake of its swooping branches, the moment of truth is fast approaching. Because summer is not that shrub’s only season in the sun. On a sunny midwinter day, when the glare is reflecting off the snow banks, evergreen foliage is likely to get scalded. Next year, consider north instead. If your plant survives.

According to Deborah Swanson, a University of Massachusetts Extension educator at the Plymouth County Extension office, when it comes to survival, “the right plant in the right location is everything.” She lacks unlimited spare time to spend preparing her garden for winter. “I don’t dote,” she says. Instead of fussing on a yearly basis, she plunks down her time investment up front, carefully choosing shrubs and trees that are reliably rock-solid hardy in Massachusetts. She suggests that other gardeners who lack spare hours do likewise. She also thinks ahead, watering newly installed shrubs and trees during summer droughts to fortify their reserves against winter stress. And she avoids plants prone to pest problems. Beyond merely sticking to worthy woodies, she also studies the site’s environment fully before installation, especially when planting broadleaf evergreens. She assesses each location for prevailing winds, proximity to an overhang, and winter sun.

It’s easy to forget to factor winter sun at planting time, but it can cause burn to the same degree that howling winds brutalize evergreens. When judging a site, keep in mind that shade from deciduous trees will no longer form a protective canopy, and sunlight is intensified by snow reflection. Also consider the compass—southern exposures generally endure the harshest winter sun. Brad Roeller, the display gardens manager at the Institute of Ecosystem Studies in Millbrook, New York, urges gardeners to place an evergreen on the north side of a protective building if that spot gets ample light in summer.

PROTECTIVE MEASURES

Positioning is paramount and knowing your territory is critical when it comes to your plants’ winter survival. Beyond that, there are no fool-proof rules. Instead, winter protection should be approached on a case-by-case basis. Whether its deer or weather that poses the threat, all gardeners should assess their needs independently. The decision to wrap or not to wrap depends more on how close your shrubs are to the road (and potential salting and sanding damage), whether sun glare is a problem, and the prevalence of howling winds than on any hard-and-fast formulas.

For gardeners who decide to take protective measures, wrapping is the most commonly suggested method. As far as antidesiccants are concerned, many experts find that these spray-on foliar coatings have little or no effectiveness in a severe winter. First of all, they should be applied when temperatures will remain above 40°F for an extended period of time. And to remain effective, they must be reapplied—at 40°F—several times throughout the season. During a bad winter (and ugly weather is what you’re guarding against, after all), opportunity may not present itself often, if ever. Furthermore, if they adhere to the underside of a leaf, antidesiccants can clog the stomata, smothering the plant.

It’s crucial to be careful when applying spray-on deer repellents to a broadleaf evergreen’s foliar surface in winter, too. Brad Roeller has experienced sunscald damage with many deer repellents, and he strongly warns against spraying during a spate of sunny weather. Better to time applications for cloudy bouts, if spray-on repellents are your chosen weapon against deer.

WRAPPING UP

As for putting your shrubs under wraps, there are certain circumstances when buttoning up evergreens is essential. Rooftop gardens are an obvious liability, as are any plantings on a hilltop, berm crest, or other exposed position. Roadside shrubs are also in clear danger (although nursery experts are apt to warn against pitting shrubs against sanding trucks in the first place).

Wrappings run the gamut from the horticultural version of haute couture to simple burlap. Whatever your style, start with an inner framework to keep the fabric clear of the foliage and prevent damage from the weight of accumulating snow. Simple furring strips are the most common underpinning.

Richard Magnuson, a landscape designer specializing in rooftop plantings in windy Boston, finds that in his line of work, winter wrapping is a do-or-die decision. First, he carefully applies an antidesiccant to evergreens in November. That stopgap measure buys a little time while he puts the finishing touches on autumn clean-up. In December, he starts wrapping. He makes a framework of sturdy bamboo stakes and then swaddles the evergreens in burlap—he buys rolls for the purpose. The seams are woven together with jute and tied firm. Then, to add a finishing touch, he winds strings of holiday lights with fresh grapevine he finds in the woods, securing the ends of the grapevine in the soil. Voila! He’s got something totally festive and fabulous to behold. But most importantly, he’s securely preserved his precious Alberta spruce, boxwoods, and the like for the coming year.

Wrapping is taken an extra mile in the Connecticut garden of Linda Allard (the recently retired director of design at Ellen Tracy, one of the worlds top fashion houses), too. There, Bud Burgess bends electrical tubing in circles to make hoops that act as a foundation for wrapping up the topiary roses. He screws them together, puts plywood underneath, covers them with burlap, overlaps the seams, and staples in the burlap to form balloons. The whole space alien-style get-up is secured with wires to keep it earth-bound against the prevailing winds.

FACING DOWN DEER

Certain shrubs are like chocolate for deer. Yew and chamaecyparis, for example, are notoriously at risk. But nothing is really safe, because deer tend to increase their menu on an annual basis, adding trees and shrubs that they formerly avoided. Although viburnum buds and pine or hemlock foliage might not be on the dining A-list, they can become a target for marauding browsers when times are lean.

So, when faced with deer, some gardeners take wrapping a step further, employing chicken wire cages. These can be put in place from late autumn through winter, stored over the summer, and kept for future seasons. At Innisfree Garden, also in Millbrook, cages are custom made for each shrub—the only problem being that shrubs tend to grow out of their clothes, just like teenagers. A constant hand-me-down system makes frames reusable.

WEIGHING THE RISKS

For all the protection wrapping offers, it also poses a few quandaries. First, evergreens are often grown specifically for their winter interest, so covering them seems counterintuitive. And, because wrappings provide a cushy shelter for little furry things seeking protection, they can court rodent damage, especially if applied before the ground freezes solidly. Time constraints often dictate what you do and do not protect.

It’s a delicate balance between ensuring that a shrub isn’t under peril versus partaking of its winter perks. If you’re dying to grow something that isn’t rock-solid hardy, you’ve got to weigh the risks. In colder regions, the risks are increased. Nancy Rose, horticulturist and educator with the University of Minnesota Extension Service and co-author of Growing Shrubs and Small Trees in Cold Climates, is a proponent of a defense strategy known as the Minnesota tip method. It’s especially popular for tender roses (hybrid teas definitely qualify for aid). Far North gardeners go out in mid-October, loosen the root system of the rose, dig a trench about one foot deep on one side of the plant, tip the canes over, and lay them in the trench. The cane is then insulated with straw (hollow straw stems tend to act particularly efficiently as insulation) or overlapping plastic bags of dried leaves, and the shallow grave is mounded with soil. In mid-April, gardeners dig up their roses and hope for the best.

Not everyone need go to the extremes that they do in Minnesota. Many gardeners check the long-range forecasts when it comes to winter roulette and decide they want to merely add a thick layer of mulch (which should always be applied after the ground freezes solid, to prevent rodent damage). As Nancy Rose points out, she grows in a climate that barely qualifies as USDA Zone 4 and sees temperatures that plummet to 25 below. And you thought that your roses have it tough. 

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