A pocketed spring assembly comprises a plurality of parallel strings of springs, each string joined to an adjacent string. Each string comprises a plurality of pockets formed along a length of the string by transverse seams joining first and second plies of fabric on opposed sides of springs. At least one spring is positioned in each pocket. Each spring has two end portions and a middle portion. The convolutions of the middle portion are greater in diameter and pitch than the convolutions of the end portions. Each interior transverse seam is cut or otherwise treated to create at least one divide enabling at least one end portion of the spring to compress without substantially compressing the middle portion of the spring.