Growing Lavender at High Altitude in Arid Climate?

I grow lavender in Taos, New Mexico. We're at 7,000 ft. altitude with arid climate and cold winters plus windy spring and summer months. All I know so far is Hidcote and Munstead are the most resistant to our temperatures. I can't grow the real French lavender here. I still have problems with some plants wintering over. I cover them with frost cloth and water them sparingly in winter/early spring. Some look so dry come spring, though.

Any ideas on how to get better results?

By Anne-Marie Emanuelli