Updated: Nov 13, 2021
Our trees are treasured possessions, adding wind protection, summer cooling, and beauty to our homes. Trees can even add 10% or more to our property values. With winter arriving soon, what can we do to maintain the health and safety of our trees?
Water well each week
Evergreens slowly lose water over the winter, and it is especially important that they go into winter well-watered. Right now, with the ongoing drought, all Minnesota trees are under stress. Without rain, mature and young trees of all types will benefit from additional water. Unless we get enough rain, plan to give each tree 5 to 10 gallons of water each week for each inch of tree diameter. For example, a tree with a 5-inch diameter can use 25 to 50 gallons of water each week. Continue until the ground freezes. To soak the soil thoroughly, water slowly.
To prevent lush new growth, which is harmed by cold, do NOT fertilize after August. Hold off until spring to add a slow-release fertilizer to give your trees a needed boost for the coming season.
Examine trees for hazards
After leaves drop, look up into the canopy. Search for broken branches, rubbing branches, crowding, cracks in the trunk, double leaders that can result in weak growth, or mushrooms that indicate rotting. Look for conditions that might cause injury to pedestrians, your home, or to your neighbor’s property. If the job can be done safely, remove dead limbs yourself. If the job is at all dangerous, hire a certified tree care professional.
Pruning of branches late in the growing season encourages fresh, tender new growth which will suffer when cold sets in. You can remove suckers from the base of the tree but wait until late spring to do major pruning because spring is when tree tissue readily heals. Clean, oil, and sharpen your cutting tools now in preparation for late spring pruning.
Mulch helps the soil to retain moisture, breaks down slowly to release nutrients to the tree, and forms a safe buffer between the lawn mower and the tree trunk. As it decomposes, mulch improves the soil structure. With newly planted trees, the mulch helps to moderate soil temperatures and helps prevent the young tree from being pushed up out of the ground due to frost heaving. If there is not much snow this winter, the soil will remain warmer under a thick blanket of mulch.
Add 4-6 inches of organic mulch out to the edge of the tree canopy (e.g., the dripline). Be sure to leave about 6 inches free of mulch around the base of the trunk to prevent growth of unwanted roots, dampness, possible rotting, or insect shelter. To prevent damage, do NOT ever mound mulch around the tree like a miniature volcano. Shred your leaves with a lawnmower and use them as mulch or get free wood chip mulch from a compost site.
Young, thin barked trees like fruit trees, crabapples, maples, lindens, and honey locust can suffer bark damage and frost cracking. Warm daylight sun alternates with night-time cold to stress and crack the trunk. Wrap the trunks with a white plastic tree wrap or a paper wrap from the soil line up to the first branches, overlapping as you go up. Be sure to remove the covering in the spring to deny a home for insects and disease.
Wrap trees for the first 1-2 winters until the bark toughens up and starts to develop furrows. In addition, you may have to wrap the tree with ¼” hardware cloth to prevent bark damage from voles, mice, or rabbits. Extend the guard 1-2 inches into the ground to discourage digging and up to a foot or two above the expected snow line. Be careful not to injure roots near the soil surface when installing hardware cloth. Repellents may work, but often need to be exchanged as animals become used to the odors.
Prevent winter-burn in dwarf conifers
Wrap them with lose burlap wrap. Special anti-drying sprays or anti-desiccant sprays are ineffective to prevent conifer damage. A barrier made of burlap or wood may prevent drying winds from harming these plants. Be sure they have adequate water going into winter.
Late fall, before the ground freezes, is a good time to get a soil test. The testing laboratory is not busy at this time of year, and you can plan your soil amendments for the coming spring. (https://soiltest.cfans.umn.edu/)
Look at your trees this winter for potential problems. Also, stop to enjoy and admire their beauty.
RCMG Garden Sage