Prewashing your fabric

 I recommend pre-washing your backing fabric to reduce shrinkage in your quilt and to remove any excess dyes in the fabric.  

I just purchased a piece of flannel for the backing of a baby quilt, and it measured 63 5/8 x 43 1/2 before washing, and after washing & drying on low heat it measured 60 1/2 x 42.  That's 3" lost through shrink on the length (parallel to the selvedges)... flannel would probably shrink more than regular quilting cotton, but that's not a given either, depending on the brand of fabric.  

applique roosters quilt

Quilted with the Argyle pattern that echoed the shape of the chicken wire print fabric in the background.

Colorful squares quilt

Quilted with the Birds Eye View pattern.