Keep de-icing chemicals from sensitive plants

Colder weather has been slow to arrive, but it's still time for Chicago-area gardeners to be prepared to protect their plants from the challenges of snow and ice.

All plants -- especially evergreens, those along parkways or near frequently shoveled areas -- are susceptible to salt and snow injury. Plants can be injured when salt-based de-icing products soak into soil with melting snow and are absorbed by plant roots. Salt spray can become airborne and coat leaves or needles of evergreen plants. And heavy ice and snow loads can break limbs.

Lessen future problems by shoveling snow quickly and before applying the smallest amount necessary of a calcium chloride de-icing product or sand. Shield evergreens and other valuable plants from salt spray with burlap barriers. Distribute shoveled snow evenly on plants and avoid having snow piled on the root zone of any one plant. Leave ice-covered branches to melt on their own, but gently sweep heavy snow from evergreens with a broom.

Here's what you need to do in the garden this month:

Trees and shrubs

h Shape and thin deciduous plants after they become dormant and until buds begin to swell in mid-March. Remove all dead or diseased wood. Then remove all suckers, water sprouts and crossing or rubbing branches. Don't leave stubs; always prune back to a bud or branch.

h Prune evergreens only in the growing season because they never become fully dormant, but remove dead branches anytime and damaged limbs as soon as possible.

h Look for insect problems and signs of disease. Egg masses of tent caterpillars, gypsy moths and tussock moths are often visible on tree branches in winter. Remove them by hand or prune out to control future problems. Check for unusual swellings, open lesions or darkened areas that could be symptoms of cankers and disease.

h Continue to water woody plants, especially newly planted trees and evergreens, until the ground freezes and during periods of thaw.

h Monitor for wildlife damage. If rodents or deer are evading physical barriers already constructed to exclude them, identify problem areas and quickly address them. Disrupt browsing patterns before they become habits.

h Protect hybrid tea, floribunda, climbing, miniature and newly planted roses. Place 12 to 18 inches of lightweight peat moss or composted manure at the bases of roses. Prune hybrid tea roses to knee height. Prune other types of roses as needed before growth resumes in spring.

Flowers

h Apply a 2- to 3-inch layer of organic mulch to perennial beds after ground is frozen hard. The mulch layer will help to minimize heaving problems caused by repeated freeze-and-thaw cycles.

Lawns

h Try to avoid walking on frozen grass to prevent broken blades and matted turf.

h Remove debris and fallen leaves from shady areas to promote drying and avoid possible problems with mold and fungus.

Houseplants

h Remove decorative foil from bottom of gift plants or punch holes in the foil to allow water to drain properly.

h Place poinsettia plants in bright light away from heating vents, fireplaces and drafty windows or doors. Maintain even moisture to keep plants from wilting.

h Give flowering azaleas bright light and occasional misting. Keep soil moist to prolong flowering. Remove old blossoms quickly.

h Water cyclamen plants only when soil is dry and avoid getting leaves wet. These plants prefer quite cool conditions. Remove faded flowers and stems to prolong tidy blooming.

h Avoid sudden temperature changes that can cause moth orchid plants to drop buds. Give plants bright indirect sunlight and moist but not soggy soil.

h Plant paperwhite narcissus in a shallow dish filled with pebbles. Space bulbs so they almost touch and cover with pebbles, with just bulb tips exposed. Water to encourage rooting but do not allow water to cover any portion of bulbs. Tie stems with raffia if they begin to flop.

h Monitor houseplants for insect problems often associated with stress from under- or overwatering, insufficient light levels or low relative humidity. Pests to look for include spider mites, scale, mealybugs, whitefly and fungus gnats. Isolate plants with problems to prevent them from spreading. Identify pests to ensure choosing the appropriate methods of control. Avoid using toxic chemicals indoors, whenever possible.