Align the springs along the webbing strips. Most chairs use nine or more springs, arranged evenly over the webbing strips. Make sure the largest part of the spring sits on the webbing if the spring has two differently sized sides.
Thread an upholstery needle with spring twine. Sew each spring to the webbing at each imaginary corner of the spring. If the chair contains cross pieces of webbing, tie two knots in the spring to one piece and the other two to the next piece. Start in the middle of the spring and work outward. Sew a continuous line of thread and do not break the string line if possible.
Tie the springs into place using a half-hitch knot. Place the needle in the fabric. Pull the needle free. Place the needle under the loop made by the first stitch. Pull the needle down through the cross that the second stitch made. Pull the thread tightly to tighten the knot.
Tie one final half-hitch knot after sewing the last spring into place.
Use the same half-hitch stitching pattern to secure the tops of the springs together. You will not sew the springs to anything, but are preventing them from springing loose and making the seat uncomfortable.
Staple a piece of burlap over the springs to protect the chair cushion from the springs and to prevent anything from falling between them.