Early snow can affect lawns and landscapes

Our area had a long fall, and the grass was still remarkably green before the recent snowfall, and many trees still had leaves. The snows of November change the dynamics of our lawns and our landscapes.

Here are the effects of fall snow on lawns, trees, shrubs, flowers and gardens.

• Recent snow fell on ground that was not yet frozen over most of the region. Snow is a good insulator and can prevent the cold from penetrating so deep into the ground. As of November 16, the ground was still not frozen at any of the North Dakota reporting points, which is much later than usual.
• Late planted trees, shrubs, perennials and bulbs enjoyed extended weeks in unfrozen soil.
• The freezing cold that arrives in the fall when the ground is bare is usually more damaging than when snow covers the ground. Snow has a moderating effect, insulating the soil and protecting perennials, strawberries and other plants easily damaged by extreme temperatures.
• Many trees were still shedding their leaves as the snow fell. Unless we get above average temperatures to melt the snow and allow for some gardening, these late leaves will stay wet and soggy under the snow cover. It will be important to remove the leaves from lawns as soon as the snow melts in the spring to prevent soggy damage from choking the grass.
  Early and long lasting snowfall can increase mold and mildew on lawns. David Samson / The Forum

• Snow mold on lawns, which becomes visible after the snow melts in the spring, could be worse this year if the snow stays longer than normal on grass that is still soft, green and lush.
• Since the grass has remained green and active longer than usual this fall, some lawn owners may not have reduced the fall mowing height. Mowing shorter before winter can reduce the likelihood of snow mold damage and reduce habitat for voles.
• Voles, also known as field or meadow mice, appear less common than in previous years, perhaps due to the cyclical nature of their populations, but for all the voles present, snow offers them protection. When deep enough, the snow allows voles to tunnel along the surface of the lawn under the snow, causing visible channels revealed during the spring snowmelt.
• The leaves of the rose bush are still a lush green, which is quite common in the fall, but the lack of early cold has allowed the roses to grow longer than normal with less chance of “lasting” or fading. harden for the winter.
  
  

  Most roses currently still have green leaves despite the snow. David Samson / The Forum

• As snow covers the rabbits’ leafy green food sources, they turn to the succulent twigs of shrubs like the burning bush, rose, spirea, hydrangea, arborvitae and others. Snow is a reminder to apply protective fences or repellents like Liquid Fence and Plantskydd to rabbit favorite plants. Rabbit activity is easily monitored after snowfall, simply by watching for tracks.
• Early snow cover that moderates soil temperature can provide a safe haven for pathogens and insects that overwinter in the soil. With less winter kill from these pests, disease and insect problems can sometimes worsen the following growing season, if soil temperatures remain mild throughout the winter.
• Grass sown after September 15 that has germinated and started to grow is more likely to survive the winter with early snow cover, compared to freezing temperatures without snow. Grass that was seeded dormant just before snowfall benefits from the protective cover.
• Winter damage to trees, shrubs and perennial roots may be less this year, compared to a dry fall. This fall’s moist soil, added to recent snow, prevents frost from penetrating so deep into the ground. Frost can spread further if the soil is dry.
• Early wet snow can weigh heavily on the flower clusters of hydrangea shrubs. Dried flowers are decorative in the winter landscape, but if the snow-laden flowers seem to cause potential branch breakage, the clusters are best cut.

Don Kinzler, a longtime gardener, is the North Dakota State University Extension Horticulturist for Cass County. Readers can reach him at donald.kinzler@ndsu.edu.