Admit the fact that you have enjoyed the spectacular fall weather and have procrastinated getting ready for winter. Warm fall days and many nights where the temperatures remain above freezing have probably given most of us a false sense of security, and some tasks have remained undone.
The big question has been, "When is it safe to turn off my sprinklers?" If you have planted fall flowers, such as pansies, they should be watered on an as-needed basis. If you have winterized your system, water these with the hose until we start getting winter moisture.Run your checklist on which plants might need additional irrigation. Anything planted this fall needs to be checked. Established turfgrass, deciduous trees and perennials that have gone dormant have little need of additional watering. Evergreens, by contrast, are still transpiring water. They may need additional water during the winter. Broadleaf evergreens are particularly sensitive to winter drying, so check them throughout the winter. These plants are best planted on the northern or eastern sides of buildings or fences so they are protected from the winter sun that heats and cools them, drying them out.
Many needle-growing evergreens routinely drop their needles at this time of year. Although the needles are evergreen, they are not everlasting. Some, such as larch and bald cypress, drop their needles each year. For unsuspecting homeowners who are not familiar with this process, this can be distressing. The process is perfectly normal and new needles will appear next spring.
A more common symptom is needle drop on Austrian and Scotch pines. Some trees shed these needles at an unprecedented rate in the fall. Count back on the branches. If the needles are at least three years old, it is natural needle drop and is no cause for alarm. (You can determine the age of any part of the branch by counting back from the tip the annual growth rings that are visible as concentric rings around the branch. Each ring is one year's growth.)
Since winter dryness causes extensive damage to other plants, take preventive measures. If you visit Temple Square to see the Christmas lights, notice that the gardeners cover many flower beds with a light-color fabric material. This spun polyester material is porous, so it allows moisture to enter and gases to escape. However, it prevents the plants from drying out and keeps the soil warmer so they grow faster in the spring.
The material is available from local nurseries and is sold as Garden Blanket or floating row cover. Put it over the beds when the temperatures drop consistently to below freezing.
Another common problem is a condition known as southwest winter injury, sun scald or sunburn. This problem occurs when the sun shines on the trunks of newly planted trees. Plants never produce heat like animals do. They are always near ambient temperatures unless something warms them artificially. On warm, bright, winter days, the sunlight on the bark raises it well above the air temperature when the bark absorbs the heat. The problem is further aggravated when snow reflects the sun's rays onto the trunk.
This reflected heat will easily raise the bark temperature 50 or 60 degrees above the air temperature. The problem is further aggravated when the sun goes down. The temperature may quickly drop 20 degrees or more. The warm temperatures during the day cause the cells to start dividing and then the rapid temperature drop and the freezing temperatures kill the cells. When the cells die, the bark on that side of the tree dies and peels away.
The way to prevent damage is not to try to keep the plant warm but to keep it at a consistent temperature by reducing the radiant heat absorbed by the plant. Lighter colors reflect heat while darker colors absorb it. Taking advantage of this physical principle means that you need to prevent the sun's rays from striking the bark or reflect the rays rather than allowing them to be absorbed.
The best way to reflect the sun is to paint the tree trunks with a mixture of 50 percent white exterior latex paint and 50 percent water. While this is acceptable for orchard trees, it may not be as attractive on landscape trees. Use a white perforated tree wrap on those trees to avoid damaging their trunks. This wrap is available from local nurseries. Do not use dark burlap or kraft paper wraps because these absorb the heat and aggravate the problem. Wrap the trees at about Thanksgiving time and remove the wrap in the spring. Do not leave the wrap on during the growing season because it may harbor insect pests.
If wrapping or painting the tree trunk is not appealing, stand a wide board on the south side of the tree to shade the trunk. Remove the board in the spring. Young fruit trees, particularly the stone fruits (peaches, cherries, etc.), and other thin-barked shade trees especially benefit from this special protection. Lindens, maples, walnuts, flowering cherries and plums are particularly susceptible to the injury.
After the trees are established for two to three years, the bark is usually thick enough so that it will not be affected and precautions are no longer needed.
Protecting plants may take extra care, but it also greatly increases the chance of their surviving the winter and the chance for strong vigorous plants in the future. Winter damage is a stress on plants and makes them more susceptible to other maladies in the future.