While we may not be thinking of them as they slumber through winter, there are still ways to help our trees get through the dormant season and thrive in spring.
1. Prevent snow pile ups
Trees well adapted to Canadian winters love snow. Snow insulates delicate roots from desiccating winds and freezing temperatures and good snow loads also mean wet soil for that important spring flush, when buds explode into flower and leaves push out.
Snow can however also cause problems. It can harbor little rodents that nibble away at the bark of young trees and branches. If you have newly-planted trees be sure to provide some protection by wrapping up small trees or low branches.
While your tree can’t have too much snow, if your soil does not drain well, it may stay wet for too long, especially if we move into a wet spring. If you have drainage problems, consider piling snow away from your tree’s critical root zone (CRZ), typically 10 cm away for every 1 cm of the tree’s diameter.
Most damaging however is salted snow. When using salt on your driveway or sidewalks, try to avoid piling the salted mush on your tree. If it is unavoidable, in spring, make sure the area around your tree gets a good drink of clean water either from rain or your hose to flush the salts out.
2. Prune for structure
A common term for arborists and nurseries, and especially important for younger trees, the goal is to choose how your tree is going to grow, training and encouraging branches you want, while taking away branches that may interfere with the tree or its surrounding infrastructure (like your house!).
While nature does a great job of pruning trees, we have often transplanted them out of their natural environment or subjected them to well-intentioned, but misguided pruning. Sometimes our trees can use a little help to avoid major long-term problems. While the pruning itself may be best left to a qualified arborist, looking at the naked branches in winter will help you start to diagnose your trees’ situation.
In winter, you will notice that your tree is not the mass of leaves as seen in the summer, but a complex dance of branches; each reaching for space, while holding on for dear life to the main trunk. The tips of branches and the unions (where branches join together) are where conflicts and failures start. Take time this winter to look at your tree’s “silhouette”, you might spot broken or hazardous branches, or finally find where the squirrel that has been stealing your bird seed is nesting.
3. Wrap them up!
While best done in late fall, it may not be too late to wrap your cedars or other cold-weather, susceptible trees, like fruit trees or those at the extent of their climatic zones.
Trees are wrapped for two reasons: to prevent snow load from breaking or bending branches, and to protect delicate leaves and buds from winter winds or ice damage. Ice damage, also known as southwest injury or winter dieback, is most apparent in spring when the tips of branches fail to leaf out with the rest of the tree. Wrapping your trees in burlap and providing wind protection can help reduce this damage.
If you notice your cedars or other trees bending from the weight of snow, it is not too late to knock the snow off and tie any branches back in place with twine or other material, but be sure to remove ties or move them yearly to avoid girdling (choking) the tree!
4. Check for cracks
During the winter, vertical cracks can suddenly appear on our trees.
A walk in the woods on a cold winter day will serenade your ears with popping and cracking sounds as water in the trunks freezes and splits wood fibres open. Often these will reopen every winter leaving visible “scars” on the trunks and branches. These wounds, while dramatic looking, are natural and most often seal up in the spring thaw. Vertical cracks, especially shallow ones like frost cracks, pose no serious threat to your tree’s health and no action needs to be taken – especially not “painting” or otherwise sealing up the injury with any products.
Horizontal cracks, or cracks that extend through your tree and down from the bottom of a “V” branch union (where a branch connects to the trunk), are more serious and a certified arborist should be called.
5. Prune for fruit production
Pruning fruit trees, such as apple, pear, and cherry, in late winter can improve fruit production.
Trees set their buds (which turn into leaves, branches, and flowers) during the previous summer, while flowers (followed by fruit) grow on one-year old branches and spurs only.
Pruning in winter clips out some of the buds reducing the amount of one-year old branches, forcing the tree to put energy into increasing the size and quality of your fruit. An added bonus of this method for those “blessed” with an annual deluge of crab apples, is a reduction of the number of fruit to roll your ankles and clog your lawnmowers!