How-to — Knife Pleating

Snip a small notch 1″ to the right of the left edge of your fabric. Next snip a notch ½” to the right of the 1″ notch. Then snip 1″ to the right of the ½” one and so on until you reach the right edge of the fabric.
Repeat from the center back point travelling to the left edge. Your fabric should look like the photograph below.

Turn the left side of the fabric so that it is away from you. With your fingers, crease the fabric at the second notch from the top. You should now have a “peak” pleat (shown as a dashed line at left). Fold this peak pleat away from you so that the first notch is creased into a “valley.”

If pleating by machine, place this first pleat under the presser foot and tack. Lower your needle into the fabric. Raise the presser foot. Crease the fabric at the fourth notch into a mountain pleat and fold it away from you, creating a valley pleat at the third notch. Continue creasing at the even notches as far as you can comfortably hold in place with your hand. Lower the presser foot, being careful that the pleats remain folded away from you. Slowly sew down the pleats, sewing less than ½” from the top edge. As you near the end of the pleats you’ve made, repeat the process. You can stop after sewing each individual pleat or sew a few at a time. When you reach the end and there are no more notches, tack and cut your threads.

To pleat by hand, pin the pleats in place so they don’t move as you sew them. Pressing the pleats with an iron will also help avoid slippage. Again, sew less than ½” from the top edge. Make your stitches small enough to keep the pleats in place. Backstitching will hold the pleats better than a regular basting stitch.