Gardenias are notoriously difficult to grow in normal indoor conditions. And in Calgary, they don’t much care for the outdoors either.
They like bright light, but avoid direct sunlight, especially during summer.
Water:Keep soil continuously moist, but reduce watering in the winter.
Temperature: Above 60ºF is preferred. Avoid cold drafts if temperature drops lower.
Soil: Use a nonalkaline soil mix, such as a rhododendron mix. They prefer slightly acidic soil.
Cold temperatures and inconsistent watering, which will cause bud and leaf drop. Common problems are insects, especially scale and aphids. A well-tended gardenia will be compact, with deep leaves, and bloom in the late summer, when the nighttime temperatures are above 60ºF and daytime temps are between 75ºF and 82ºF.