Some kinds of shrubs are especially vulnerable to winter, and gardeners often try to protect them with sheets of burlap.

Before you do, “make sure it’s really necessary,” said Julie Janoski, Plant Clinic manager at The Morton Arboretum in Lisle. “Wrapping up plants to protect them from winter can do more harm than good.”

Burlap that is wrapped all around a shrub can collect snow that weighs down the branches and may break them, she said. When the snow melts and spring rains begin, the soaked fabric can trap moisture on the plant’s foliage, which can encourage fungal diseases.

For certain plants, burlap, which can be purchased at landscape supply companies, can be helpful during winter. For example, it may be used to protect broad-leaved evergreens such as boxwoods and azaleas whose leaves can easily dry out; hybrid tea roses and big leaf hydrangeas that aren’t quite hardy in Chicago’s cold weather; or any evergreens such as arborvitaes that are exposed to salt from nearby sidewalks, streets or driveways.

“The plants you might consider protecting are the ones that actually had a serious problem the previous winter,” she said. “Don’t wrap plants up just in case.”

Burlap is best used to erect a vertical screen or fence around a shrub to protect it in winter, rather than wrapping the fabric around its leaves and branches. (Beth Botts)

The best way to use burlap is not to wrap the plant’s leaves and branches, but to create a barrier against wind or salt. Staple burlap to stakes pounded into the ground to support a vertical screen on the problem side of the shrub, or to create a fence around it. For example, you might make a burlap screen along the driveway to intercept salt spray, or as a windbreak on the side of the prevailing wind to protect a tender shrub from icy blasts.

The vertical burlap won’t collect snow and will leave the shrub open to air circulation, so its leaves can dry off after a rainstorm or after snow melts. Keep the burlap a few inches clear of the plant.

A shrub can still be damaged in a severe cold snap if it has an underlying problem such as disease, or if it suffers from lack of water.

“The most important thing you can do to protect evergreen shrubs over the winter is to water them throughout the summer and fall,” she said. If the shrubs don’t have enough water stored in their leaves or needles, a burlap screen can’t keep them from drying out.

To reduce the risk, “choose the right shrubs in the first place,” Janoski said. For example, junipers can handle the effects of salt better than boxwoods or arborvitaes, and they might be a better choice near a driveway or sidewalk.

The Plant Clinic can help you select plants suitable for your situation.

“Choosing the right plants can reduce the need for maintenance tasks such as creating winter protection,” she said.

For tree and plant advice, contact the Plant Clinic at The Morton Arboretum (630-719-2424, mortonarb.org/plant-clinic, or plantclinic@mortonarb.org). Beth Botts is a staff writer at the Arboretum.