Once all the rows are joined together measure the length of the quilt and then sew two 3½ inch strips to the sides. This should measure 46½ inches. Finally measure again and add strips to the top and bottom of the quilt, this should measure 42 inches.                                                       

Once the 4 crosswise rows are stitched together, measure them and then cut 3 strips the same width from the sashing fabric. If your seams were accurate this should measure 30½ inches.

Sew these strips between the rows, but not to the top and bottom.

Finally add the outer border to the quilt, top and bottom first from the width of the fabric and the two sides last from the length of the fabric.
 If you are using a directional fabric make sure everything is the right way up.