Winter protection of ornamentals
Within the last decade we had a couple of winters that brought cold and snowy weather. I can remember in a recent December our area receiving maybe six inches of snow in one event. I can also remember one spring after one of those cold winters where I received many phone calls and conducted numerous site visits because of cold damage to woody ornamentals.
The cause of the winter damage most of the time was improper pruning time by the property owner. The clients had been pruning at the wrong time for years and the real cold and snowy weather of that winter finally caught up to them.
Today, I am going to share information on winter protection of your ornamentals by use of a UGA publication by Bob Westerfield, UGA Extension horticulturist, and Orville Lindstrom, professor of horticulture.
With the weather still warm right now, thinking about winter protection of your ornamentals may not be high on the list. Keep in mind that in late summer and early fall plants will start preparing themselves for winter by cold acclimation. This activity is started by cooler temperatures and the shorter day lengths that will happen this time of year. Note that cold acclimation needs to happen in a timely fashion. If the acclimation happens too early, the growing season of the ornamental will be shortened. If the acclimation happens too late, the plants can be hurt or killed by early frosts.
Our information states that local weather conditions, the plants selected and plant maintenance activities in the growing season can affect the timing and extent of cold acclimation. I am not going to go into detail on the types of cold damage, but just know that cold injury can happened on all parts of a plant. You can see cold injury on fruit, stems, leaves, trunks and roots. Some injuries you can see such as to the leaves. If the roots are injured, you may not notice till the plants fail to leaf out in the spring. How can you help prevent cold damage to your ornamentals?
One of the first tips in prevention is in the actual section of the plants themselves and the area you choose to plant them in the landscape. Try to select plants that can handle the cold temperatures in the area where you live. Look for plants that meet the minimum cold hardy requirements for your part of the state. I will add to just not consider cold weather, but select plants that can handle the summer heat too. Do not forget planting site selection.
Investigate your property to figure out the locations that get the coldest and the warmest. A tip is that during the winter, the coldest spots are normally found on the north and northwest sides of the property and also in low areas where the cold air will settle. On the flipside, the southern part of the property will normally be the warmest. Keep microclimates in mind too. This is where you can place your cold sensitive plants near the part of the house that gets more southern exposure or even near larger plants or other structure types.
Proper plant nutrition can help a plant be more tolerant to cold. This includes fertilizing at the right time of year too. Note that fertilizing after August or September with a high nitrogen fertilizer can cause problems. This can cause a lot of new growth which will be more susceptible to cold damage. I mentioned this in the opening paragraph, but proper pruning is important.
Pruning in the late summer or early fall can cause a flush of new growth that is more susceptible to cold injury. I remember for years keeping a pruning chart for the various landscape items at my computer. Make sure you know the proper pruning time for your ornamental plants. Do not forget about proper transplanting too. Note that plants transplanted in the late fall or early winter having a greater chance of cold injury due to possible lack of acclimation. You need to transplant in early fall. Windbreaks can be beneficial.
Our info states that fences, buildings, evergreen plantings and even temporary structures can help protect plants from cold. Windbreaks give more help with cold winds and what we call advective freezes. This type of freeze is when temps drop because of invasion of cold air masses. Windbreaks normally help if on the northwest side of the ornamental planting. There are other preventative tips that our space will not allow to cover today, but do keep one thing in mind on container plants.
If you leave container plants outside, you can push those containers together. Mulch or cover them to decrease heat loss. You can even wrap the container bases in plastic, burlap or blankets to help trap heat too. Covering plants with sheets, blankets or even cardboard boxes are suggested in times of cold weather. We do not recommend covering plants with plastic.