Rick Durham, Consumer Horticulture Extension Specialist, University of Kentucky
 
Winter houseplant care.

Winter can be especially hard on houseplants since light levels tend to be lower, the air is drier, and we being creatures of habit, do not generally adjust watering and fertilizing rates to match the reduced growth rates of our houseplants.
    Light. Low light is the biggest problem for most plants grown indoors in any season, especially winter. If possible, try to move plants to a south-facing window. In the northern hemisphere, a southern exposure may actually get slightly more sunlight exposure in winter than other times of the year since the arc of the sun's travel across the sky is lower and more southern in orientation. However, the frequency of overcast skies and shorter daylength means the overall light intensity of winter is reduced. To counteract the low light levels of winter, consider adding some supplemental lighting to your plants. Fluorescent tubes, either warm or cool white, are best, and it is not necessary to buy tubes that are specially formulated for plants when some natural light is available. Even providing supplemental light for a few hours a day will greatly enhance the appearance of your plants.
    Humidity. The second biggest culprit for poor winter performance of indoor plants is low humidity. Without some type of humidifying effort, the home's relative humidity during winter is near 10-15%, especially in drafty areas near heating vents. This is a similar moisture level to a dry dessert. Such dry air will cause the leaves of many tropical plants to turn brown around the edge and other plants may drop leaves all together. To remedy this situation, try grouping plants together and keep them in a more humid room such as a bathroom, kitchen, or laundry room. You could also place plants on a tray filled with gravel and water, but make sure the pots are not actually touching the water in the tray or the soil will remain too wet. Using some type of home humidifier is most effective and will make winter living a little more comfortable for humans and plants alike.
    Water and Fertility. Realize that plant growth slows down in winter and watering and fertilizing should be reduced as well. Summer or winter, the best way to determine whether a plant needs water is to stick your finger into the potting medium at least to the first knuckle. If you feel moisture, you should hold off on watering until the top inch or so of the potting soil dries out. When you do water, water thoroughly and allow the excess to drain off. Too much water is the leading cause of death for houseplants. With plants growing slower in winter, it may be best of hold off fertilizing all together.
    Cold Windows. Remember most indoor plants are of tropical origin and may exhibit low temperature damage even if temperatures stay above freezing. Sometimes indoor plants suffer "frostbite" if they are in contact with a cold window pane. Also, don't close your plants behind drapes at night since the temperature can easily drop below their tolerance level. If damage does occur, it's best to cut away damaged areas.
 

Things to do in the landscape in February.

• Be careful when applying salt for ice removal to driveways and sidewalks. Such material can damage landscape plants either by direct contact or from runoff into nearby beds or turf. Plants that are particularly susceptible are arborvitae, beech, hollies, dogwood, hemlock, and pines. As an alternative to salt try sand, sawdust, or fertilizer as a remedy to icy areas near plantings.
• Once perennials are dormant, it is fine to apply a thicker layer of mulch (8-12 inches) to protect them during the coldest part of winter. This can be materials such as loose soil, pine branches, pine needles, straw, loose compost, etc. The key is to avoid compacting the mulch so that plants beneath are not suffocated. Also, the material should be removed once the ground has thawed in early spring.
• Keep watering landscape plants throughout the winter when the soil is not frozen. This is especially important for evergreens since they continue to use and loose water through their leaves all winter long.
• Check stored plant material (roots, corms, tubers {such as potatoes}, bulbs) often for damage by rodents or disease. Remove any damaged material quickly and do not allow rot to set in. Rot may quickly spread through the stored material, especially if rodents or insects are present.
• Apply a spray of dormant or horticultural oil to landscape plants that are infected with scale. Follow label directions carefully. It is best to apply the oil when temperatures will be above freezing for a few days, even warmer weather into the 40's is best. The oil acts by suffocating the overwintering insects.
• Start thinking about pruning those fruit trees in the backyard. After severe winter weather is over and just before new growth begins in the best time to prune. That means for Kentucky, anytime from late February to late March is generally the best time to start. Contact your local county agent for more information about pruning.

 

February is a good time to start thinking about pruning fruit trees. It's best to prune most fruits while the plants are still dormant but after the severe weather of winter has past. This means late February and early March are the ideal times for pruning in Kentucky. Fruit trees are trained and pruned to two basic growth patterns, the central leader, used for apple, pears, and some plums, and the open center, used for peaches, nectarines, and plums. Regardless of growth patterns, there are two main types of pruning cuts used, thinning out and heading back. Thinning out, removes an entire shoot back to a side shoot or scaffold limb. Thinning cuts open up the canopy to sunlight and air penetration and usually do not invigorate growth of the tree. Remove the shoot flush to the side shoot or scaffold limb without leaving a stub. The presence of a stub tends to delay healing and may promote the growth of unwanted suckers. Heading back, removes only the terminal portion of the shoot. Heading back cuts promote the growth of lower buds as well as several buds directly below the cut. Cuts made into one year old wood tend to invigorate growth by promoting branching directly behind the cut. Cuts made into two year old wood tend to be less invigorating and serve to help conform older trees to their allotted space and shape.
     The central leader. The central leader tree is characterized by a single, central, upright trunk referred to as the leader. The main branches coming from the central leader are called the scaffold limbs and are positioned so that they are not directly above one another. The lowest 4 to 5 scaffold limbs are usually 24 to 36 inches above the ground to allow ease of movement of lawn and garden tools and equipment under the tree. Scaffold limbs should meet the trunk at an angle of 60-90 degrees. Branch angles at the lower end of this range can be increased by wedging toothpicks (when the limbs are first forming) or wooden spacers (for older branches) between the trunk and branch. Above the first whorl of scaffold limbs, a space of about 18 to 24 inches is left free of branches to allow light to penetrate into the center of the tree. A second whorl of 3 to 4 scaffold limbs is selected with a second segment of bare trunk left for sunlight penetration. Limbs and bare space alternate up the tree to allow good sunlight penetration all the way up the trunk. The training of a tree to this pattern will require 4 to 5 years or more. Once the basic central leader pattern is established, future pruning will more or less maintain the mature shape of the tree. A modification of the central leader system (the modified central leader training system) is sometimes used for pears. Instead of a single, central trunk, multiple central trunks are maintained. The modified central leader is used for pears because of their susceptibility to a bacterial disease, fireblight. Once infected with fireblight, diseased branches must be pruned from the tree. In the modified central leader system, an infected leader can be removed without drastically affecting the architecture of the tree.
    The open center. The open center tree has no central leader. Rather, a single whorl of 3 to 5 scaffold limbs are established approximately 30 to 36 inches above the soil surface. As with the central leader systems, these scaffold limbs should branch at 60 to 90 degrees from the vertical center of the tree. The open center allows for maximum sunlight penetration into the center of the tree. This is particularly important for vigorously growing fruit trees such as peach. The open center will also allow good air movement into and through the canopy which will help reduce disease pressure.
    With both systems, dormant pruning should involve both heading back cuts and thinning out cuts. Thinning out cuts are used to eliminate diseased or unproductive branches. Also remove branches that are crossing and those that shade one another. Water sprouts or suckers that are vigorous upright branches growing from main branches should also be removed by thinning out cuts. Heading back cuts are usually made about one quarter of the way back from the terminus of a branch. Heading back cuts are used to encourage side branches and to stiffen the remaining branch. With apples and pears, fruit buds are produced on two to three year old wood or compact stems called spurs. Heading back cuts strengthen such wood so that it will support a heavy crop load. With peaches and nectarines, flower buds are produced on one year old wood. Heading back cuts on peaches promote new growth that will produce the flower buds for next year's crop. If pruning cuts are made correctly, healing will be fairly rapid. The use of pruning paint or wound dressings spray to the wound may be used for aesthetic reasons but such treatments will not hasten healing. While the dormant season is the most important time to practice pruning, don't forget that some pruning during summer is also appropriate. If growth from heading back cuts is too vigorous, removal of some of the new growth by thinning out may be beneficial. Also, if the canopy is dense, remove some limbs during summer to open the canopy to sunlight and air penetration. And vigorous water sprouts or suckers should be removed as soon as they are noticed.
    Another thing that needs to be done during the late dormant season (mid March or so) is an application of dormant or horticultural oil to fruit trees. These oils are specially formulated products and differ from motor oil or vegetable oils used for cooking. Horticultural or dormant oil is a very good chemical that has minimal impact on the environment and usually has little effect on beneficial insects in the landscape. Dormant oils target overwintering pests such as scale and certain mites. The oil acts by suffocating the pests. One precaution with the use of oil it that it should not be applied during extreme temperatures. Avoid applying oil when the temperature will drop below freezing the day before or the day after application. Also, avoid application if the temperature will rise above 90F - a rare occurrence in mid March. As will all chemicals, be sure to read and follow label directions when applying.