Winter Damage to Evergreens
Winter Damage to Evergreens
Winter is coming. Winter weather can take a terrible toll on our beautiful evergreens.
Prevention of winter problems takes place at planting time. Choose evergreen varieties that are hardy in our area (USDA hardiness zone 5 or lower).
Choose a good location. You will want to grow a healthy tree that withstands the rigors of our winters. De-icing salts can cause salt injury to pines, spruce and fir that are planted within 6o feet of roads or close to driveways. Foliage facing the street may turn brown at the tips by spring.
Dissolved salt can also enter the root zone and weaken or kill the plant.
Another injury similar to salt damage, desiccation injury, can occur when evergreen leaves and needles dry out during the warmer winter days. The leaves become active and frozen roots cannot resupply needed water. Colorado Blue Spruce, Eastern White Pine, Red Pine, and Yew can suffer from such winter injury. Tender evergreens can be planted in protected areas away from direct, intense sunlight, sheltered by more resistant plants, and protected by a burlap screen or snow fence. Antidesiccants, such as Wilt-Pruf, are not very effective in preventing winter drying.
Do not prune or apply nitrogen fertilizers after early August. Other?wise, tender new growth will not harden in time for winter. In autumn, continue watering your plants until the ground -freezes (at least 1" weekly, or more in sandy soils). Avoid overwatering. Mulch with 4 or 5 inches of straw, leaves or wood chips after the ground has frozen to moderate the soil temperature and conserve moisture.
Heavy snow can break the branches of evergreens such as yew, arborvitae and juniper. In late autumn, prevent this by encircling the branches of the entire bush with cord and drawing it snug. Be sure to remove the cord in spring. Snow loads can be gently brushed from evergreen branches; move the broom upward to prevent breaking the branches. If the branches are covered with ice, leave them alone as they are very brittle and may break easily.
In winter, limit the use of de-icers on your steps, sidewalks and driveway. De-icers will not remove a 5 or 6 inch snowfall. Remove as much snow as possible first. Mix the deicer with sand to improve traction on the slippery ice and to reduce the need for excess de-icer. Calcium chloride and calcium magnesium acetate (CMA) are the more environmentally friendly de-icing salts.
If winter damage does occur, wait to see if the plant recovers by late spring. Sometimes, especially if damage is mild, new bud growth will replace the dead spots Trim out all dead, dying, diseased or crossed branches. Scrape the branch gently with your fingernail or knife to see whether the under-bark is green and alive, or brown and dead. Cut back to the next branch or to 1/4 inch from the next living bud.
Larger branches should be cut back to the tree trunk. Never leave a stub, since this opens up the tree to disease. Do not cut flush to the trunk of the tree, but cut back to a slight bulging area of the limb called the branch collar.
To prevent ripping of bark below large branches, make a partial undercut about a foot out from the trunk. Next, cut off the limb about a foot and a half from the trunk. The last and third cut will remove the limb stub and will he just on the outside of the branch collar. New growth from the branch collar (like a doughnut growing inward) will eventually cover the wound.
Paint or other covering is not recommended and can seal in disease organisms. If the damaged limb or tree is really large, if power equipment is needed, or if the tree has become a hazard to you or your house, be safe and hire a professional arborist to do the job.
Lastly, fertilize and water your plant with tender loving care. Help your winter-stressed tree or shrub recover full health.