Winter Protection
Trees, shrubs and evergreens
Several types of winter plant damage occur in the Calgary area. The most obvious type, referred to as tip-kill or die back, is a result of warm, dry Chinook winds, bright sun, and low relative humidity. These conditions accelerate the normally slow loss of water from plant tissues and result in dry twigs, damaged buds and dessicated evergreen foliage and the death of certain plants.
Warm Chinook winds also cause plant injury by inducing premature spring. This occurs when plants break dormanc y and begin growing during extended periods of warm winter weather. Subsequent cold periods damage developing leaves, crack sap-filled bark; and, on occasion, damage shallow root systems. Frost damage, caused by rapid temperature fluctuations, is a condition we should therefore be aware of and attempt to prevent.
Protected or sheltered gardens have a better chance of standing up to the warm, dry winds of Calgary. Shelter may be provided by houses, walls, fences, or even by other trees. The most sheltered spots in your yard are located where the snow drifts the deepest. Snow protects plants by insulating them from winter temperature extremes. But snow often doesn’t accumulate in this area, and many new gardens lack shelter entirely. We have to offer a helping hand when it comes to winter protection.
Start by encouraging deep root systems by deep root watering during the growing season. Also, always give your plants a generous watering just before freeze up. A well watered deep root system is well protected from the influences of Chinooks.
Use mulches (ie.wood chips) or plant groundcovers over the root areas of your plants. This prevents soil moisture loss in winter or any other season and ensures consistent, cold soil temperature throughout the winter. Apply extra mulch to the soil surface around the base of less hardy or newly-planted trees and shrubs. Examples: compost, dry leaves, straw or other dry plant material. Apply plenty of water in late fall before the ground freezes and if necessary, water trees and shrubs in winter during Chinooks to reduce and replace soil moisture loss. Areas that dry out first include south facing slopes or near the foundation on the south side of your house.
Some evergreens, especially newly planted ones, may need more than a sheltered location, mulching and watering. Examples: In late fall, after generous watering, apply an anti-desiccant such as Wilt-Proof to sensitive evergreens. Create extra protection with a windbreak or sun screen by placing two or three stakes into the ground 12-18 in.(30-45cm) from the tree on the sunny or windy side, and stretching burlap between the stakes. (picture of burlap screen)
Tea roses and tender roses
Since tea roses are grafted onto hardier root stock, the most important aspect of winter protection is keeping the plant alive above the graft. The bush should be planted so that the graft is 4” to 5” blwo ground level, wher the temperature is much more consistent. Soil is then used to further protect the plant. In the fall, after light frist, water the plant well, and cut back to about 8-10”. Place a rose cone, a large tree pot with the bottom removed, or a heavy, waxed cardboard box over top of it, and fill the box with soil, vermiculite, peat moss, straw, sawdust, or dry leaves. Cover the top with a cloth, not plastic, and don’t remove the cover until early May. You may have to cover again temporarily if frost is expected. While this method is not guarantee that every tea rose will survive, it is quite successful most of the time, and means that tea roses can be grown successfully in Calgary. It can also be used to protect other less hardy shrubs, such as an azalea, blueberry, clamatis, rose daphne, rhododendron and weigela.
Climbing Roses
Since mose climing shrub roses bloom most heavily on previous year’s growth. It is most important that the bushes survive well above ground, in order to have maximum number of flowers. Non-hardy climbing roses are not recommended for Calgary gardesn because they are not reliable. Some Explorer series roses such as William Baffin and John Cabot are much hardier and will bloom reliably. Rambling Roses such as John Davis and Henry Kelsy may also be trained as climbers.
