Sunshine, sunshine, sunshine!
All types of lavender need full sun to thrive. Native to the western Mediterranean, lavender is a sun worshipper and can take up to six hours of direct sun daily.
Drainage & Soil
Lavender loves dry soil, and needs good drainage to avoid root rot. If you think of France, those plants are growing in soil, heavily mixed with limestone which is naturally alkaline with high pH levels. The only soil that it really doesn't like is clay.
Time & Temperature
The best time to plant lavender in Ontario is usually in May depending on the weather. Some suggest that you wait until your ground temperature hits 12 degrees C. If you plant too early, the plant will become vulnerable from the cold and wet soil.