The Prairie Hardy Expert Guide to Winterizing Young Fruit Trees and Shrubs for the Canadian Winter
Whether you live in Central Alberta, Saskatoon, or Northern Ontario, winterizing young fruit trees and shrubs in Hardiness Zone 3 or colder requires careful planning and timely actions to ensure their survival through our harsh winter conditions. Living in Zone 3, characterized by temperatures that can drop as low as -40°C, presents unique challenges. These tips will be helpful for anyone growing fruit trees in the Canadian climate.
Here is our comprehensive guide to help you prepare your trees for the Canadian winter:
Pruning and Clean-Up
Pruning is a task best left for early spring, as the pruning wounds need to heal, which occurs once the tree comes out of dormancy. Unless you have some dead or diseased branches, in this case, you could carefully remove them as needed.
Rake up and compost fallen leaves, dropped fruit, and plant debris around the base of your fruit trees and shrubs. If you have any disease or pest on your plant material, it would be best not to compost it on site but to dispose of it appropriately to avoid spreading any unwanted pests or diseases.
If you suffer from Apple Maggots, you must promptly remove and dispose of any dropped apples. You do not want these apples to rot and the maggots to burrow into the earth, creating ongoing problems year after year. Diligence is critical here.
When in doubt: MUCLH!
As you know, we recommend mulching your trees as soon as you plant them in spring, but autumn is an excellent time to revisit your trees and add more mulch if needed to help protect the roots for the upcoming winter season. Apply a thick layer of mulch (4-6 inches) around the base of young fruit trees and shrubs. Use materials like wood chips, straw, or shredded leaves. Mulch insulates the soil, helping to moderate temperature fluctuations and retain moisture, and is necessary for weed suppression. Avoid piling the mulch directly against the trunk. Ensure the mulch extends outward to cover the root zone, ideally out to the drip line; the larger the area, the better! What can we say: the trees love mulch!
Watering trees before the Winter Freeze-Up
We recommend thorough watering throughout the season for bare-root trees planted in early spring and slowing down (or stopping altogether) after the long weekend of September to help the trees go dormant. The occasional rain may be enough here; you do not want to stimulate any new growth now.
In late fall, once your nut and fruit trees are dormant and right before winter freeze-up (usually around late October), give your tree a thorough watering. This is important; it helps to protect the root systems from frost penetration, which can dry out and damage your tree. Frost penetration is a primary concern when there is no snow for protection and the temperature drops. The water will freeze and thus insulate your tree roots.
Do Not Fertilize!
We recommend topping the root zone with aged compost and a thick layer of mulch in springtime.
If you wish to fertilize, the window is early spring, when the plant starts its active development, and no later than early July. We urge you to stop fertilizing after July 1st for our Prairie and Canadian climates, or your trees may not go dormant in time for the arrival of the cold winter. Fertilization can stimulate new growth that will be vulnerable to winter damage.
Protecting Young Trees and Shrubs from Critters
You must pamper and give extra attention to fruit and nut trees. These trees are commonly affected by rodents and bark-loving animals. Could you imagine having all your trees girdled by voles in one winter, causing them to die? This is possible without proper protection! Throughout the growing season, voles will have plenty of greens; however, when food is scarce in fall and winter, they will eat the bark off your trees. Adding a roll of hardware cloth (see pictures; please use 1/4 inch or smaller) around your trunk will significantly help. Please make sure to stake your added protection so that it does not rub against, or break your young tree!
The same goes for deer and moose. They might come and prune your tree from above. It's tasty for them, but not fun for you! Protect your precious trees by adding adequate fencing; this can be done around your orchard area or by adding some staked fencing around an individual tree.
Snow, your new best friend
Snow acts as a natural insulator. The snow layer can protect the plant from extreme cold; we encourage piling extra snow around your delicate plants to help insulate them for winter. You could even shovel extra snow into the hardware cloth around your tree. Always be careful not to bend or break delicate branches. If you are worried about icing during spring thaw, sprinkling some dirt on the snow can significantly speed up and soften the melting process.
Sun-Scald (Southwest Injury)
Sun-scald, also known as Southwest Injury, is a significant tree threat, particularly during a Prairie winter. The sun can heat the bark on cold winter days and stimulate activity. The bark temperature drops rapidly when the sun sets, killing the active tissue. We do not believe this to be a major concern for young whips, but it becomes more so when the trunk reaches a significant size of over one inch or more.
The most common method used to prevent sun scalding on the trunks of trees is to wrap the tree up to the first branch with a white tree guard protector. This guard will effectively reflect the sun's heat off the tree. Please check this spiral twice a year to avoid pinching into the growing trunk. Some growers prefer white interior latex paint (not oil-based) on the southwest side of their tree trunks.
Areas in southern Alberta where the Chinook wind is active are particularly prone to sunscald. Fruit and nut trees in these areas need extra care, and they suffer more losses due to the temperature extremes and continuous melting of the snow.
Monitor your Trees
Periodically check your winterized trees for signs of damage or stress. Ensure that mulch remains intact and that wrapping materials are not harming or rubbing againt them. Enjoy the dark days of winter, a great time to dream and plan for the next growing season.
Following these detailed steps will give your young fruit trees and shrubs the best chance of thriving through the cold Canadian winter and emerging strong in the spring. Winterizing correctly is crucial for their long-term health and productivity.
Best of luck, and have a great autumn season - don’t be intimidated, and remember to take one step at a time. Patience is crucial; whether you are a beginner or an expert grower, there is always more to learn and experiment with!
Greetings from Kristel, Prairie Hardy Nursery.