Tree root systems vary with the variety, but all have one feature in common: they must be kept hydrated or they will die---along with the tree. From spring to fall, watering is a function of rain or irrigation systems, but winter presents unique challenges to gardeners who grow trees in Canada's frozen ground.
Canadian growers must prepare trees to survive winter, monitor them for signs of winter browning and protect the roots from frost heave damage or repair it when it happens to maintain healthy specimens.
Hydrate trees thoroughly before freeze-up to prevent browning. Soak spring-planted trees two to four hours twice a week for the first two to three months and then weekly. Water established trees deeply during dry periods. Add peat moss to sandy soils to improve water retention. Create a hollow around the tree base that will retain water in dry areas. Water trees slowly with a soaker hose to encourage deep roots.
Water less often as temperatures plummet to ensure the roots get enough oxygen. Give conifers more water than deciduous trees. Soak trees deeply just before freeze up and again after the second heavy frost to hydrate them for the long winter.
Mulch around the base of the tree with pine boughs, grass or straw to provide a bed for snow cover after the ground is frozen. Environment Canada suggests stacking straw bales on the southeast of the tree base to retain snow and trap moisture. Monitor the snow cover and shovel more mulch on as needed.
Wrap cedars and other tender evergreens in protective burlap in late fall. Push bamboo stakes into the ground on opposite sides of the tree in an upside down 'V.' Wind burlap around the outside down to the roots. Hold it in place with clothespins or rope. This protects the needles from winter kill by the drying sun and wind and keeps branches from breaking under the weight of snow.
Check trees for frost heave damage after warm periods. Rapid changes in temperature from hot to freezing can cause the soil to crack, exposing the roots to air and drying them out. Immediately fill any cracks with soil and mulch with layers of insulating snow, straw or soil. Water roots deeply as soon as the ground thaws.