Hollies, especially evergreen varieties, can often be damaged by extreme winter weather. Here are a few tips for heading off some of the most common problems.
1. Siting makes a difference
When the ground is frozen, drying wind and harsh winter sun can cause leaves to lose water faster than the plant’s roots take it up. The resulting tissue damage is known as winter burn. Siting an evergreen in a location that is sheltered from afternoon sun and prevailing winter winds may be enough to prevent the worst damage.
2. Create some shelter
If a plant is in an exposed spot, drive stakes around the dripline and wrap burlap or canvas around the outside of the stakes, leaving the top open. This temporary winter structure will act as a windbreak and sunscreen while still allowing for healthy air circulation around the plant.
3. Water and mulch with care
Young and old plants alike will appreciate a deep weekly watering until the ground is frozen or covered by snow. A 2- to 3-inch layer of wood chips or bark mulch over the root zone will help conserve soil moisture, but be sure to keep the mulch at least a few inches away from the base of the plant to discourage rodents from girdling the trunk and lower branches.
4. Watch out for heavy snow
To prevent a buildup of snow from splaying or breaking branches, gently brush or shake snow off as it accumulates. If ice builds up, however, it is best not to handle the plant, as this is likely to cause further damage.
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Jim Resch, PhD, chair of the Research and Development Committee of the Holly Society of America, grows and evaluates new holly cultivars. Mary Tipping is the curator and plant recorder at the Scott Arboretum of Swarthmore College in Swarthmore, Pennsylvania.