If I had to guess what most people have been thinking about recently, it would be the extremely frigid temperatures we have been experiencing. But, what about your outdoor plants? What do they do to get through the cold?
A plant's ability to survive freezing temperatures depends on that plant's ability to acclimate to the cold. Certain environmental stimuli such as short-days and low temperatures in the fall trigger changes in the plant that allow the plant to survive the cold. One of the first changes the plant undergoes is going dormant. Then when below-freezing temperatures set in, the plant takes water out of its cells. The area between the plant cells freeze, protecting individual cells from damage.
While we know this, what we don't know is why certain plants can tolerate the cold more than others. Therefore, when purchasing plants it is best to determine what USDA plant hardiness zone you live in (either 3 or 4 around here) and only landscape with plant that can survive winters where you live. Even if you only use plants that are hardy to this area, it also helps to know about the most common types of winter injury and how to manage these injuries.
Desiccation occurs when plant material dries out and is seen more often in evergreens because they keep their needles year-round. This injury causes needles and leaves to look discolored or burned. Desiccation occurs when water leaves the plant faster than it can be taken up. Strong winds are one reason plants may lose water. Sunny weather is another. Because our soils freeze during the winter, it is difficult for plants to take up water that is lost during the winter months.
Properly watering your plants is one of the best ways to prevent desiccation from occurring. If autumn rains have been insufficient, give your plants a deep soaking to the entire root system just before the ground freezes. Water your evergreens if we have a warm spell and the ground unfreezes. This is especially important in February and March as the sunlight becomes more direct. Mulching helps maintain uniform soil moisture around the roots and helps decrease the chances of desiccation. Homeowners can also protect small evergreens by making windbreaks out of burlap or canvas. These reduce the force of the wind and shade the plant. Avoid using plastic as a wrap. Too much heat builds up in the plastic.
Anne Lenox Barlow is the horticulture educator with Cornell Cooperative Extension in Clinton County. CCE offices may be reached in Clinton County at 561-7450; Essex County, 962-4810; and Franklin County, 483-7403. E-mail your questions to askMG@cornell.edu.