Groundscape, a Fort Worth Tx Landscape Company, installed concrete edging / curbing around flower beds and tree rings. GroundScape, http://www.groundscape.com , used rebar inside the concrete to make sure the concrete does not crack when the ground shifts.  This concrete flower bed edging and tree ring is just one of the many ways to provide a barrier and prevent wash out of mulch and soil.  If you would like a quote please call GroundScape at 817-759-0102 or visit us at www.groundscape.com.