Autumn to Winter Tree Care: International Society for Arboriculture
“While your trees seem to be in a state of hibernation in the winter, exposure to the tough conditions can cause them major stress,” says Jim Skiera, Executive Director of the International Society of Arboriculture (ISA). “Minimize stress by helping your trees through the cold months, a little at a time. If you take care of your trees in the winter, you’ll be rewarded in the spring.”
Rely on mulch. Put composted organic mulch under your tree in the fall or early winter to help retain water and reduce temperature extremes in the soil. A thin layer of mulch will act like a blanket and give the tree’s roots a little extra protection.
Give your trees a drink. Winter droughts require watering as much as summer droughts. If temperatures permit, an occasional watering during the winter on young trees can be a lifesaver. But be sure to water when soil and trees are cool but not frozen.
Fertilise them, too. Urban landscape trees can be growing in soils that do not contain sufficient available nutrients for satisfactory growth and development.
Fertilising a tree can improve growth; however, if fertilizer is not applied wisely, it may not benefit the tree at all and may even adversely affect the tree. Mature trees making satisfactory growth may not require fertilisation. When considering supplemental fertiliser, it is important to know which nutrients are needed and when and how they should be applied. Soil conditions, especially pH and organic matter content, vary greatly, making the proper selection and use of fertiliser a somewhat complex process. When dealing with a mature tree that provides considerable benefit and value to your landscape, it is worth the time and investment to have the soil tested for nutrient content. Any arborist can arrange to have your soil tested at a soil testing laboratory and can give advice on application rates, timing, and the best blend of fertiliser for each of your trees and other landscape plants.
Prevent mechanical injuries. Branch breakage or splitting can be caused by ice and snow accumulation or chewing and rubbing by animals. You may prevent problems with young trees by wrapping their base in a hard, plastic guard or a metal hardware cloth. Wrapping trees with burlap or plastic cloth also can prevent temperature damage. However, it is important to remember to remove the wraps and guards in the spring to prevent damage when the tree begins to grow. Other damage can be caused when plowing or shoveling snow. Be mindful of trees nearby. Damage to limbs and trunks from plow blades or a sharp shovel can be detrimental to trees.
Prune your trees. Autumn is a good time to prune your trees. Not only are trees dormant in the colder months, but it is also easier to see a tree’s structure when there are no leaves on the branches. “Proper pruning is vital to the health of trees and plants, in part because it helps relieve stress on trees and keeps them growing,” says Skiera. “Just be aware that each tree is different, and pruning at the wrong time or the wrong way can injure a tree making it more susceptible.”
Since autumn is the time of year for colorful, falling leaves, many people do not realize that it is also a prime time to plant new trees. After cooler weather has set in, conditions are perfect for stimulating root growth in new trees. Once roots are established throughout the fall and dormancy of winter, spring showers and summer warmth encourage new top growth. Fall is the optimum time to plant balled and burlapped trees and shrubs. However, all bare root plants should be planted later in the season, when they are completely dormant. Here’s the best way to prepare and plant a new tree this fall:
Preparing the Tree
• For bare root trees, neatly cut away any broken or damaged roots. Soak the roots for a few hours prior to planting to allow them to absorb water.
• Container-grown trees should have the plastic or metal containers removed completely.
• Carefully cut through the circling roots. Remove the top half of pressed peat/paper containers.
• Balled and Burlapped (“B&B”) trees should have all the ropes cut. Pull the burlap at least one third of the way down and slit the remaining burlap to encourage root growth. If in a wire basket, cut away the top of the basket.
• Remove all tags and labels.
Planting the Tree
• Dig the planting hole shallow and broad. The width should be two to three times the diameter of the root ball and the depth only as deep as the root ball.
• Gently place the tree in the hole, ensuring that it is perpendicular to the ground. Once you begin to backfill, it will be difficult to reposition the tree.
• Partially backfill with the soil from the hole, using water to settle the soil. Finish backfilling the hole while gently but firmly packing the soil. Be sure that you leave the trunk flare (where the roots spread at the base of the tree) visible above the soil.
• Soak the soil well, making sure no air pockets form between the roots. Wait until next year to fertilize.
For more information on fall and winter tree care, or to find an ISA Certified Arborist, visit www.treesaregood.org.
The International Society of Arboriculture (ISA), headquartered in Champaign, Ill., is a nonprofit organization supporting tree care research and education around the world. As part of ISA’s dedication to the care and preservation of shade and ornamental trees, it offers the only internationally-recognized certification program in the industry. For more information, contact a local ISA Certified Arborist, found at www.treesaregood.org.