Lavenders Hardy for Zone 4

I see from your catalogue that there are dozens of lavender varieties.
I want to plant a lot of lavender but don't know what would be the best variety for fragrance and winter-hardiness. I live just south of Peterborough, Ontario, Canada and think I'm in zone 4a(?).
Is there someone that could recommend what plants to order.
I will order Richters plug trays for next spring planting once I know what to order.

Hidcote and Munstead lavender are the only varieties hardy in zone 4. To make sure that a snowless winter with fluctuating temperatures does not kill the plants anyway, mulch them heavily with straw or hay in the late fall and remove most of this mulch in the spring. We have found that twickle purple lavender is almost as hardy as the above mentioned varieties and may survive your winters too- with the mulch. All of these varieties are selections of the English lavender and as such have what we consider the best fragrance.