Winter Preparation for Ornamental Plants

Since many plants are stressed, basic winter preparation work is all the more important. The first step in avoiding winter damage or injury is to select plants that are winter hardy for your area. Healthy, well maintained plants in general will survive the winter better. Below are several items to consider in preparing plants for winter.

Woody Plant Preparation

Adequate watering is essential in the fall to assure that plants go into the winter months with a good supply of moisture in the soil around the roots. This is especially true for plants susceptible to winter burn such as broadleaf evergreens (azaleas, hollies, boxwoods and rhododendrons), narrowleaf forms (junipers, yews and arborvitae) and plants susceptible to salt damage.

Fall is an excellent time to fertilize landscape plants. Although the tops of the plants appear dormant, root growth (and thus nutrient uptake) continues late into the fall. For more information you can call our office and request a copy of "Fertilizing Woody Plants."

One way to help prevent rapid moisture loss through the leaves or needles is with antitranspirants. These are wax-like products which are sprayed on the leaf surfaces to slow down transpiration. Antitranspirants should be applied before severe winter sets in.

Other types of cold injury include sunscald and frost cracks, which occur due to extreme temperature fluctuations. Sun scald is actually a freezing injury and is most likely to occur on young trees. Sun scald spots may develop into a frost canker. Use tree wraps on susceptible trees to help reduce extreme temperature fluctuations. Frost cracks occur when the outside cells of the tree lose water, shrink and pull apart, causing a crack to open longitudinally with the grain of the wood. Again, tree wraps may help, but some species are simply more prone to cracking than others. Sometimes trees shaded on the south and west sides, where the tree heats up the most, will crack less.

Herbaceous Plant Preparation

Strawberries should be mulched to protect the plants against damage from extreme cold winter weather and from heaving during alternate freezing and thawing. Use a loose organic material such as clean wheat straw. Apply mulch after several frosts in the fall but before the temperature drops below 20 degrees F - generally between mid-November and mid-December in Illinois. Apply 100 to 150 pounds of straw per 1,000 square feet (2 to 4 bales) 3 to 4 inches deep over the plants.

Perennial plants also require fall maintenance activity. Remove any excess growth and either burn (if legal) or compost the plant material. It may be advantageous to leave some of the stems so that they can catch leaves - this will help protect the plants. It is also beneficial to mulch perennials after the ground has frozen. Use something that is loose and does not pack down or stay too wet. Perennials vary in their cultural needs, including winter protection; therefore, you may need to research the specific needs of your plants.

When preparing roses for winter, hybrid teas, floribundas, grandifloras and polyanthas should be pruned back slightly if the canes are excessively long in late fall. It is also a good idea to rake up any fallen rose foliage, especially if blackspot was a problem. Cover the plants after they go dormant. Bushel baskets or commercial covers work well. You will need to trim the canes back to fit underneath the cover. Other ways of protecting the roses include using leaves (oak work best), pine needles, straw, old sawdust or bark chips. The depth of the material should be 12 inches. Soil is not recommended since it stays too wet and packs too much. In the spring, remove the cover or mulch, trim the canes back to healthy wood (just above the strong bud), and thin the plants to 4 or 5 canes.

Climbing and rambling rose canes may also need winter protection. Lay the canes on a bed of straw and cover with more straw. Be sure to cover the crown. Keep the straw in place by tying or covering it with a small amount of soil. In the spring remove the covering, remove all damaged wood, and place the canes or shoots back on the trellis.

Houseplants that summered out-of-doors should be inside by now, but if they are not, don't delay in bringing them in. Isolate the plants from those already in the house until they are determined to be pest-free. Monitor the watering carefully; they will not require as much water as they did outside. Expect some leaf drop due to acclimatization to lower light levels.

Compost Bins

Compost bins should be turned before cold weather sets in to add air to the pile and encourage decomposition.

Leaf Removal

Leaf removal should be done in the fall not only for aesthetic reasons but because many leaves house pathogens capable of causing disease the following year. Do not allow leaves to lie on the grass as damage can occur. Dispose of leaves through community programs or use them yourself as mulch or in a compost pile.

In sum, the more work done through the fall and winter, the less spring cleanup required. Be sure to properly discard all plant wastes. Do not remove winter-protective devices too early in the spring. In areas subject to many late heavy snowstorms and temperature extremes, early mulch removal might be a serious mistake.

For more information call us at 773-233-0476 for a copy of "Winter Protection for Woody Plants."

Winter 1996
Winter Preparation for Ornamental Plants | Deicing Salt Can Injure Plants | Bug Bites: Woolly Worms | Hort Shorts | Hort Tips | Food Safety: A Procrastinator's Guide to a Safe Holiday Dinner | Food for Thought: Help! Refrigerator Overload! | Healthy Cooking: A Quick Start Breakfast | Health and Household Tips

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