Protecting plants in winter
The winter storm that hit central Illinois recently played havoc with driving conditions, holiday plans, and area trees and shrubs. The heavy snow that fell the day before Thanksgiving knocked branches and, in some cases, entire trees to the ground. But the snow sure was great for making snowmen.
Most winter damage to landscape plants is the result of heavy snow, ice, and wind, which cause branches to bend and break. Trees with multiple leaders (Bradford pears), clump trees (river birch), and upright evergreens (arborvitae and juniper) are among the species most susceptible to this type of damage. Proper pruning to eliminate multiple leaders and weak branch attachments will reduce the likelihood and severity of snow and ice damage. If winter branch breakage does occur, remove the limbs as soon as possible -- hanging branches can be a danger. Use clean, sharp cutting equipment; a wound will heal faster when a clean cut is made rather than a ragged tear.
Another winter problem is sun scald on newly planted trees and trees with thin bark. Sun scald occurs when the sun heats bark to the point at which cells below the bark become active. When the sun is blocked, bark temperatures drop rapidly, killing active cells and causing sunken, dried, cracked areas of bark. This damage usually occurs on the south or southwest side of a tree. Trunks of thin-barked trees such as crabapple, maple, linden, honey locust, cherry, and plum should be wrapped to reflect the sun and keep the bark at a more constant temperature. A commercial tree wrap, burlap, plastic cloth, or plastic tree guard should be put on the tree in the fall and removed in the spring, after the last frost. Wrap new trees for at least two winters. Older trees are usually not affected by this type of winter injury because the bark can insulate tissues and protect cells from the sun's heat.
Evergreens are subject to desiccation, or drying out, during the winter. Desiccation is caused by wind and sometimes by the sun. Winter winds can increase the rate of transpiration of the plant; in other words, if the ground is frozen, the plant cannot take up more water to replace the water lost in the leaves, causing the plant to dry out. The foliage becomes discolored, usually brown, or burned. Proper placement of evergreens in the landscape is the first step to minimizing this kind of winter injury. Also, evergreens need adequate moisture. This means keeping evergreens watered through the growing season, into the fall. Plants in exposed areas may need additional protection. Options include loosely wrapping plants with burlap or putting up a snow fence.
Another practice to prevent some winter damage is to mulch plants. It's not too late to apply a three- to four-inch layer of organic mulch (e.g., wood chips, decomposed shredded leaves) around perennial plants, trees, and shrubs. For disease and insect control, keep the mulch pulled back a few inches from the stem of the plant. Mulch will help minimize water loss and soil heaving (from freezing and thawing cycles), which can damage roots and new plantings. In addition to mulching, allow dead plant material to remain on perennial flowers until spring; this may help protect the crown of the plant.
Winter is a great time for gardeners to start planning for summer. The University of Illinois Extension Sangamon-Menard Unit and the Springfield Civic Garden Club are sponsoring a "Garden Basics" series of seminars designed to provide basic gardening information to homeowners.
The two-hour seminars run for five consecutive Tuesdays, beginning at 6 p.m. Jan. 25. The topics cover the basics on plants, soil, flowers, trees, and pests. Instructors are educators and specialists with the U. of I. Extension.
A fee of $25 covers the cost of all five sessions and a class notebook. Seminars will be held at in Extension Building No. 30, on the Illinois State Fairgrounds. Registration by Jan. 14 is encouraged because class sizes are limited.
For more information, call 217-782-4617. Send your registration fee to the Sangamon-Menard Extension Unit, P.O. Box 8467, Springfield, IL 62791.