Advice needed for winter hardy raised bed
I'm an avid gardener, but have never used raised beds.
I just built a semi-circular retaining bed next to my raised garden pond which is located in the middle of my back yard. The retaining bed is about 36"x24", 18" tall. It is made from large stones. I filled it with equal parts soil and compost. I planted Japanese Forest Grass and Sedum autumn joy.
Also, I'm planning on building some raised beds for my mixed herbs, probably about 4x3, 12" high.
The raised beds are relatively small so I'm wondering if the winter freeze will kill the roots of these plant? Any thoughts?