Protecting Plants Against Cold And Wind Isn't Just Hot Air

January 01, 1998

UNIVERSITY PARK, Pa. -- Plants don't like to be out in the cold wind any more than people do, but a gardening expert in Penn State's College of Agricultural Sciences says savvy gardeners can protect plants from wind and cold injuries.

"After plant tissue freezes, it can lose considerable amounts of moisture," says J. Robert Nuss, professor of ornamental horticulture. "Because the trunk and soil are still frozen, it is impossible for the plant to replace lost moisture in the stems and foliage."

Nuss says broadleaf evergreens such as Japanese and American holly, rhododendrons and mountain laurel are particularly prone to wind and cold injuries. He points out that once moisture levels within a plant drops below a critical point, the affected tissue dies off.

"Obviously the best protection against wind injury is to reduce the amount of air moving past the plant," Nuss explains. "Luckily, some plants stand up to wind better and can be used to shield or protect less durable species."

Nuss says needle evergreens can be used as wind barriers, citing such species as large juniper shrubs, pine or spruce species if space permits, and Japanese yew shrubs.

Nuss says gardeners can easily see where wind speeds are higher by observing wind patterns. Narrow areas between structures and bed areas that extend beyond an exposed corner of a structure will receive the greatest air movement.

"Look for snow drifting patterns and where there is no snow cover," Nuss says. "In these areas, use only the hardiest plants or deciduous species that are less susceptible to wind damage."

Some wind-resistant deciduous species include privet, forsythia and lilac.

Nuss also recommends other wind barriers.

  • Fences. Fences will not stop wind, but they can slow wind speed and channel it away from garden sites.
  • Screens. Well-placed or well-designed screens can enhance the landscape and protect plants all year, Nuss says. "Screens will function as snow fences, so place them so snow will not accumulate on walkways and drives."

Injuries from the cold are harder to prevent, and roots are harmed more easily than top growth. Nuss says gardeners can take a few precautions to reduce or prevent low-temperature root injury.

  • Snow. An insulating layer of snow over the root system can protect roots from low temperatures.
  • Mulch. A layer of mulch will help reduce temperature fluctuations in the root zone and prevent the roots and soil from drying out.

"Every species has a minimum tolerance level for temperatures," Nuss says. "It's best to research the plantings in your garden to see if the plants can stand up to typical winter temperatures in the Northeast."

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EDITORS: For more information, contact J. Robert Nuss at 814-863-2196 or John Wall John_Wall@agcs.cas.psu.edu 814-863-2719 814-865-1068 fax

Last Updated March 19, 2009