Squared borders are added first to the sides of the quilt center, then to the top and bottom. Lay the quilt top flat on a large table or the floor. Lay both border #1 side strips down the vertical center of the quilt top and smooth carefully into place. Slip a small cutting mat under the quilt top (you’ll need to do this at the top and the bottom) and use a rotary cutter and ruler to trim the border strips to the same length as the quilt top. Matching centers and ends, sew the border side strips to the quilt. Gently press the seam allowances away from the quilt center. Repeat this process along the horizontal center of the quilt, including the newly added borders. Repeat for any remaining borders.
Mitered borders are added by sewing border strips to all sides of the quilt center and then mitering each corner. When joining each border strip to the quilt, begin and end stitches ¼" from the quilt top corners and backstitch. Referring to the diagrams, fold the quilt right sides together diagonally at one corner. Flip the seam allowance toward the quilt top, match seam lines and pin through both layers about 3" from the corner. Place a ruler along the folded edge of the quilt top, intersecting the final stitch in the border seam and extending through the border strip. Draw a line from the stitch to the outer edge of the border. Pin together along the pencil line. Sew along the line to the edge of the border; backstitch. Trim seam allowances to ¼"; press open. Repeat for all corners.