TIL my local nursery had two types of lavender, and I had to pick one for my window box.
The choice was between English lavender, which is hardy for our zone 5 winters, and French lavender, which has those pretty little 'rabbit ear' flowers but might not survive a freeze. I went with the English type, and it's already starting to smell amazing on my sunny kitchen windowsill. Has anyone here tried growing French lavender in a colder climate and had it come back?