Winterizing Landscape Shrubs

Preparing shrubs for winter

Shrubs form the backdrop to your landscape's splashes of floral color and often take a starring role with their own showy blooms. Well-formed, healthy shrubs take a long time to grow, and they can add significant value to your property. A well-established shrub generally needs little maintenance, but harsh winter weather can damage your valuable plants, especially young or recently transplanted shrubs. A little preparation in the fall will help protect your shrubs against the cold winter months ahead.

Prevent them from drying out

Desiccation, or dehydration, can be a big problem for shrubs in the winter, especially evergreens. Conifer shrubs, azaleas and other evergreen shrubs continuously lose water through their leaves, and they cannot take up additional water during dry winter weather or if the ground is frozen. Strong winter winds speed up this drying process, making a few precautions essential.

To help prevent desiccation, be sure to water evergreens thoroughly in the fall before the ground freezes. Spread

mulch around the shrub to protect the roots and conserve moisture and spray the stems and foliage of sensitive evergreens with an antitranspirant such as Wilt-Pruf before the temperatures drop below 40 degrees. You may need to reapply an antitranspirant midway through winter, but don't apply it during freezing temperatures.

Helping plants conserve water becomes especially important if you are planning to move shrubs to different areas of your landscape after they go dormant. As with evergreen shrubs, it's important to prevent transplants from drying out during winter weather. Make sure the transplants have plenty of water, and apply an antitranspirant a few days before planting.

Roses, too, can benefit from an antitranspirant spray to help prevent dehydration. In addition, although it's best to reduce watering in the fall to allow roses to go dormant, if the weather is extremely dry, water them about every three weeks throughout the winter.

Mulching: not just a springtime chore

Mulching provides many benefits to plants throughout the year. It promotes healthy root activity, controls weeds and helps prevent erosion. As you are getting your shrubs ready for their winter rest, remember that mulch also helps moderate soil temperatures and conserve moisture. In colder regions of the country, freezing and thawing cycles can damage bark and leave the roots of recently planted shrubs exposed to the elements. Mulch helps prevent these cycles that can push weak-rooted plants out of the ground.

As you head into the winter months, check to see that an adequate layer of mulch surrounds your shrubs, especially evergreens, young shrubs and weakened or damaged plants. If needed, apply a layer of mulch before the ground freezes. Use an organic mulch, such as hardwood tree bark, spreading it to about 2-4 inches deep.

Avoid piling mulch against the base of woody stems; it can serve as a home for disease-causing organisms or insect pests. Rake the mulch back six inches from the base of the shrub after applying.

Prune gently

Aside from aesthetic appearances, pruning helps promote vigorous growth and encourages shrubs to produce more flowers and fruit. Pruning can also help promote air circulation, which will help prevent disease and insect pest infestations.

Pruning timing depends on the type of plant. For most deciduous shrubs, early fall pruning is best limited to light thinning cuts, as shearing off the tops of plants promotes new, tender growth that won't harden off in time for winter and can be damaged by the cold. (Thinning cuts involve cutting a lateral branch all the way back to the main branch, as opposed to shearing the outer shape of the shrub.)

It's best to wait until late fall or winter when plants are dormant to do any heavier pruning, although you can remove damaged, diseased or dead branches and suckers any time of year. Fall is also a good time to trim long rose canes, which can be damaged by winter winds.

Note that summer-blooming deciduous shrubs, ideally, should pruned in late winter or early spring and spring-blooming deciduous shrubs should be pruned in the late spring after flowers have dropped.

When pruning and doing other fall cleanup-chores, be sure to save trimmings and leaves for the compost pile. Use a chipper/shredder to break up large or tough branches and help them decompose faster. Remember to exercise caution when using chippers, pruning tools and saws.

Other cold-weather concerns

Flower buds and shoots can be damaged by a sudden, unseasonal cold snap in the fall. This damage is commonly known as cold injury. In cases of early frost warnings, cover shrubs with plastic or burlap to help protect them. In extreme cases, you can also place a light bulb under the plastic to generate additional heat.

In colder regions of the country, snow serves as a form of insulation to help protect plants, but if it piles up too high on fragile shrubs, it can cause branches to break. Gently knock off excess snow after heavy snowfalls, and use a snow barrier to help prevent drifting if necessary.

Come spring, gypsy moths, tent caterpillars and bagworms all can cause damage to leaves with their voracious feeding. You can help prevent infestations by knocking down and destroying their egg masses in the late fall and winter.

You may also notice animals gnawing on your shrubs during the winter months. If this has been a problem in the past, the fall is a great time to set up wire barriers around vulnerable areas.

Do you have a tip to share for preparing shrubs and other plants for the winter weather? Post it below in our comments section!

Sources:

Complete Guide to Trees & Shrubs. Published 2004 by Meredith Books; Des Moines, Iowa. How To: Landscaping Basics. Published 1997 by Time-Life Books; Alexandria, Virginia.

Wilt-Pruf Plant Protector home page. Wilt-Pruf Products, Inc. Accessed Sept. 20, 2010, at http://www.wiltpruf.com/

“Winter Protection for Your Roses.” By Stan Barrett, Master Gardener, Colorado State University Cooperative Extension, Denver County. Accessed Sept. 20, 2010, at http://www.colostate.edu/Dept/CoopExt/4DMG/Flowers/Roses/wintrose.htm