Snow or lack thereof - effects on landscape plants

Last Updated: 
January 6, 2006

BEND, Ore. – With snow season upon us, home gardeners should know that the fluffy, white stuff can actually benefit plants during freezing winter weather – if you are lucky enough to have much.

Snow is an excellent insulator and can protect landscape plants from the devastating effects of repeated freezing and thawing, explained Amy Jo Detweiler, horticulturist with the Oregon State University Extension Service.

Flower bulbs and garden root crops, in particular, will benefit from an insulating layer of snow. Plus, the added moisture when the snow melts is good for plants.

For your plants’ sake, use snow mulch only where you are sure melting snow will drain away easily and efficiently. Do not pile up a lot of snow in areas around the house where drainage is poor. Too much snow can result in unwanted quagmires around the home. Waterlogged soils in the spring can stress or even kill some plants.

Landscape plants under eaves are often drought-stressed. Detweiler suggests moving some of the snow shoveled off driveways and walkways and pile it around plants under eaves that may have escaped coverage by snowfall.

In the drier, colder parts of the state, there may not be enough snowfall to protect plants and provide moisture. Cold weather and desiccating wind combined with sparse snow cover can damage plant root systems.

Landscape plants including woody shrubs and perennials in central and eastern Oregon may need supplemental water during extended dry periods in the winter.

As in wetter or snowier parts of the state, shrubs growing under the eaves of a house are particularly susceptible to damage during dry spells.

Winter drought-damaged plants are often so weak they do leaf out, but then may die. Others die from drought stress during the winter months. These plants may appear to have been killed by the cold, but more likely the cause is desiccation.

During winter dry spells, when there is little or no snow on the ground, a deep watering every six to eight weeks will be enough to keep plants from drying out. Water only when the air temperature is above freezing, and early in the day so the water will have time to soak in before nighttime freezing.

Another wintertime concern for eastside gardens is sun-scald. Trees with thin bark – such as maples, ash and aspen – are particularly susceptible to sun-scald when young, before their bark has thickened. A paper wrap (available at garden stores) can be used during the winter months, but should be removed in early spring when growth resumes. This wrap can be used for 2-3 years until young trees develop thicker bark.

Author: Carol Savonen