Hi Phil, Spanish lavender is suited to overwinter in your hardiness zone and should do just fine outside in your area, even with temperatures in the 40s.
You can add a little mulch on top of the soil to give the roots extra protection against lower temps and when winter weather is expected to be more severe, move it to a sheltered area to protect against winds and temperature drop. If it gets to a point where you are concerned about your lavender plant surviving the outdoor elements, simply move it indoors and place it on a sunny windowsill.
Hi Phil, Spanish lavender is suited to overwinter in your hardiness zone and should do just fine outside in your area, even with temperatures in the 40s.
You can add a little mulch on top of the soil to give the roots extra protection against lower temps and when winter weather is expected to be more severe, move it to a sheltered area to protect against winds and temperature drop. If it gets to a point where you are concerned about your lavender plant surviving the outdoor elements, simply move it indoors and place it on a sunny windowsill.
Hope this helps!