Cold winds? Mine are not happy - I lost some in the winter, and parts of the survivors are dead. I'm heaving a sigh and replacing them at the moment.

In my area, root rot fungus frequently does that, though usually in the summer.

I find this variety of lavender is inclined to do that, particularly after a winter, when it can look very scraggly and unattractive.

True.....sadly. I am beginnning to regard them as annuals!