Recent cold temperatures left their mark in more ways than one. In addition to dead batteries in the car, frozen water pipes and other maladies, the cold has a profound effect on plants, both indoors and out. Recent news reports have chronicled the potential damage to fruit crops and even fruit trees.
While it is too early to assess the total damage, it appears that some stone fruit, particularly the peaches, may have already been damaged. What can you do about the problem? There is little, if anything, you can do except avoid future damage. Delay pruning until you can assess the damage to the plant's woody parts, buds and flowers. There is no cure in terms of a spray or any other application to overcome effects of the cold winter.Ornamental plants are also affected by the cold. Broad-leaf evergreens, including euonymus, laurels, holly and others show severe dieback from the cold temperatures. Again, the plants lose their leaves, and some will suffer dieback of the wood. Fortunately, because of snow cover around the base of the plants, they will come back up from the roots. Many of these plants are rated for hardiness, zone six, and suffer damage when we have severe temperatures.
Another interesting phenomenon that occurs with extreme cold is frost cracks, which occur in the trunks of trees. They are the result of the wood, which has a high moisture content, freezing solid. The resulting split leaves a gap in the bark. This generally closes naturally and the bark overgrows the damage after several years. There is only one thing that can be done. If the crack penetrates the tree, the tree should be bolted together to help restore structural strength. Bore a hole through the trunk and place a bolt with a large washer on either end. If the crack is long, put a bolt every 2 to 3 feet down the trunk. Those bolts become a permanent part of the tree as the wood grows over them, so remember their location if you attempt to remove the tree in the future.
In addition to damage to outdoor plants, many indoor plants experience problems from cold weather. Most indoor plants are from tropical regions and show damage when the thermometer dips below 45 degrees. The symptoms vary according to the plant, but the leaves usually turn black or brown, then dry out or turn into a green slime. If damage is severe, the plants will die. Plants show damage after short, brief exposure to cold temperatures.
Even though the furnace thermostat is set at 70 degrees, the home is not 70 degrees. Frost on the windows indicates interior temperatures at that point have reached 32 degrees. Tropical plants placed near the window suffer damage when exposed to these cold temperatures. Another popular location for interior plants is the entryway of businesses or homes. Exposure to a blast of cold air from the outdoors can cause severe damage to interior plants quickly.
A similar problem related to the cold is relative humidity. The greater the temperature difference between the outside and the inside temperature, the lower the relative humidity inside. Increasing humidity is important to the survival of interior plants. In most cases, interior humidity with forced-air heating is 10 percent or lower. By comparison, the relative humidity in the Sahara Desert averages between 20 and 25 percent.
Humidities are increased by grouping plants together, by running a humidifier or by constructing a pebble tray. Pebble trays are easy to construct and are effective. Take a leak-proof pan and fill it with pebbles or marbles. Add water to the tray so that it comes within about a quarter-inch of the top of the pebbles. Set the pots on the exposed pebbles or marbles. The pots should always sit on top of the stones, which evaporate water around the pot and increase the humidity. This helps prevent damage to plants in the dry interior air.
Inside and outside plants are a great addition to our environment. They increase our enjoyment of nature and make our surroundings more attractive. They are susceptible to environmental problems, including the recent cold temperatures. As much as possible, protect your plants from temperature extreme and other problems, and you'll be rewarded with beautiful additions to your interior and exterior landscape.