The Balcony Garden Site
The balcony garden is L-shaped and faces south and east. It is located in downtown Calgary, Canada. It has cement floors, brick walls, two exterior lights and one electric plug in. It measures about 16.25 square metres (175 square feet). Half of the balcony has cement walls, the other half, facing south, has a metal railing and is open to the elements.
Calgary’s growing season is about 115 days. Our plant hardiness classification is Zone 3a, but balcony gardeners here often garden in microclimates that expand plant selections and extent our growing season.
The Wacky Weather
There is no place in the world where you’ll find greater day-to-day weather changes than in Southern Alberta. Frost can occur most months of the year. Calgary’s climate is greatly impacted by its altitude, latitude and proximity to the Rocky Mountains.
Calgary ranks number one in Canada for the most sunny days year-round. The city’s latitude means winters are cold; our altitude means summer nights are cool. The average mean temperature is 4ºC (39ºF), the average low and high temperature is -2ºC (28ºF), and 10ºC (50ºF), respectively. Calgary’s annual precipitation is 420 millimetres (16.5 inches) and 20 per cent falls in the coldest six months of the year.
Calgary has unpredictable springs and short summers. Spring can start early and last for four months, with extremes in temperature. Spring brings the biggest storms, the biggest snowfalls and large amounts of precipitation. Average precipitation in May is 60 millimetres (2.4 inches). June is the wettest month of the year with 80 millimetres (3.1 inches). July is the typically the warmest month with average lows of 10ºC and highs of 23ºC. Fall is dry with 10-15 millimetres (0.4-0.6 inches)of precipitation and no big storms.
January is the coldest month with a mean temperature of -9ºC, and an average low and high temperature of -15ºC (5ºF) and -3ºC (37ºF) respectively. Winter temperatures vary greatly, especially with Chinooks, but are typically cold. Winters are also very dry. February’s precipitation average is just 8 millimetres. A Chinook can raise Calgary’s winter temperatures 15ºC (59ºF) in a few hours and can last for a day or two.
It’s very difficult to over-winter any plants on the balcony. The alpine troughs are left to fend for themselves each winter, uncovered and tucked up to the patio windows. About one third of the plant material survives the winter. The troughs are lightly watered in the fall until they freeze up and sometimes throughout the winter, depending on temperature variations and Chinooks.
Generally in Calgary the northwest quadrant of the city is the coolest and windiest as it is at a higher elevation. The southwest quadrant is wettest. Northeast Calgary is considered the driest as it is in a rain shadow created by Nose Hill. The southeast quadrant of the city is generally considered the warmest, as it is at a slightly lowest elevation.