Lavender in Muskoka (Zone 4)

I live in Muskoka which is zone 4, with lots of snow cover. I have problems growing lavender. What type of lavender would be best for this area? I put in Lady Lavender last year. It did real well but I'm not sure if it will back this year. I would appreciate any suggestions. I visit your greenhouse 2 or 3 times a year. I would like to buy a tray of Lavender if you could suggest one that is suited for this area.

Lavender is not reliably hardy in Zones colder than Zone 5. However, there will be microclimates that are warmer-or colder than the surrounding area and you should be able to find some spots that will support lavenders. Pick the hardiest variety- I would suggest Munstead lavender and plant it in a very sheltered but sunny, well-drained spot. Ideal growing conditions make for better hardiness.