University of Maryland Extension

December Tree and Shrub Tips

evergreens covered in snow
Norway spruce. Photo: Robert Videki, Univ. of GA,

(More tips from HGIC)

  • In a “normal” year in our region we do not get much ice or snow in December but if we do, try to prevent it from building up on gutters and eaves above shrubs. Heavy snow and ice loads can break branches. Using an upward motion, gently sweep snow loads off of shrubs to prevent breakage. Sweep snow and ice off shrubs with an upward motion.
  • Trees and shrubs can be pruned now. Remove dead or diseased branches and make any necessary cosmetic cuts. Remove broken branches and make pruning cuts back to healthy wood. Extensive pruning of spring flowering plants such as azaleas, rhododendrons, and dogwoods will reduce the amount of blooms in the spring. If you do not desire to reduce flowering, wait until after they bloom next spring to prune them. (Watch our pruning videos)
  • Evergreens such as hollies, boxwoods, and pines can also be moderately pruned this month. The trimmings can be used for Holiday decorating.
  • You can protect shrubs from winter winds by surrounding them with burlap or cardboard or constructing small, solid windbreaks located 18 inches from the plant on the windward side.
  • It is still a good time to mulch your landscape if you haven’t done so already. Mulch should be applied only 2-3 inches deep around ornamental plants and kept away from shrub and tree trunks. Voles are active all year. Round and deep mulch makes a favorable habitat for voles. If the mulch is next to woody plant trunks, the voles will feed on and damage bark and wood.
  • Trees and shrubs can be fertilized as long as the ground is not frozen. It is rarely necessary to fertilize a mature tree. Newly planted and very young trees benefit the most from tree fertilization. Woody plant roots continue to grow in early winter and can benefit from the added nutrients. It's important to protect our watershed by not overusing fertilizers. If your landscape plants are growing well and are already at the size wanted, there is no need to fertilize them every year.
  • Although it is the beginning of winter, newly planted trees and shrubs need water on a regular basis if it is dry. This is especially important for broadleaf evergreen plants such as rhododendrons and azaleas that become “winter-burned” from a combination of frozen soil and a lack of available moisture in the root zone.
  • Nursery stock trees and shrubs can be safely planted until the ground freezes. Always carefully examine trees prior to purchase to assess quality. Remove container stock plants to examine root systems. Avoid trees with dead roots or those that are circling the trunk.
  • It is too late to transplant trees or shrubs from one location to another in the landscape. Most will not get established enough to survive the weather.
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