Awasome Garden Fence Rodent Raised Bed References. You can stop them with some 1/4″ grid hardware cloth. Web removable raised garden bed fence.

Two 1″ x 2″ x 8′ wood furring strips (pine is standard, but you may opt for a nicer quality wood. Web if you don't already have a fence, then build one. The case for natural pest control think of your garden as an ecosystem that needs diversity to thrive.