Some preventative measures for growing in Chinook country.
Hardiness zones are based on weather records of the average coldest temperatures of a region. Although Calgary and Edmonton are both in plant hardiness Zone 3a, some plants that thrive in Edmonton may struggle here. To garden successfully in Chinook affected southern Alberta we need to consider other environmental factors. These factors include strong winds in summer and winter, low levels of rainfall, unreliable snowfall and Chinooks. Chinooks form when an Alaskan low-pressure area draws moist Pacific air over the mountains. When this system reaches the eastern slopes it gathers more heat and becomes even drier. Chinook is an aboriginal word meaning "snow eater". We have all witnessed this when one snowy winter day may climb from -20C to +10C in a matter of hours.
Winter injury is more common in trees and shrubs that enter winter stressed, so practicing the following protective measures is the best course of action.
Mulch: Mulch in both summer and winter. Mulch will hold the soil in place when damaging winds can blow away precious topsoil. Winter mulch protects plant roots from extreme temperature fluctuations. Summer mulch retains moisture and suppresses weed growth. Apply bark mulch to a depth of 10cm (that is 4 inches for those of us over 40) and re-apply each spring and fall to maintain this level. Avoid laying mulch so that it makes contact with the tree or shrub, as it can cause the bark to rot.
Water: Watering deeply twice a week is much better than frequent light watering. Watering in the morning is the best time to avoid water losses through evaporation in our scorching hot summer days. Good water management practices will insure that plant roots can tap farther into the soil and survive periods of drought. A final heavy watering between late October and mid-November will fill soil with moisture before winter arrives.
Fertilize: Newly planted trees and shrubs should be fertilized with Phosphorus, shown as the high middle number on fertilizer products, to develop strong roots. Established trees and shrubs benefit more from an all-purpose fertilizer. Stop fertilizing with Nitrogen towards the end of July to allow plants to harden off and go dormant before winter. Choose the right plant material: If you are adventurous, it is fun to try a less hardy plant in a sheltered location to see if you can push the limit. You may be pleasantly surprised at how well it does. Contact the experienced staff at your local garden center for information on hardy plants for your region.
How often have we heard the remark that anybody can garden in Vancouver but the best gardeners live in southern Alberta? Beautiful gardens thrive here in spite of the challenging conditions we tackle. We really do have a varied selection of trees and shrubs to choose from that grow well in our region. All it takes is a little preparation and maintenance to have the landscape you have always wanted.