How to Keep Slipcovers in Place
- 1). Measure along the seat of your sofa, loveseat or chair from arm to arm. Subtract 2 inches from the measurement.
- 2). Put the slip cover on the piece of furniture and tuck it in snugly on all sides.
- 3). Cut the broomstick or 1-inch-diamter dowel to size with a saw if necessary.
- 4). Push it down all the way in the back of the sofa, pulling the fabric at the back edge of the seat seam down into the crevice with the dowel. In some sofas there may be a little resistance before the dowel pushes down in the joint between the seat back and seat under the cushion.
- 5). Smooth out any wrinkles. If you need to adjust the drape of the slipcover, remove the dowel, pull the fabric down or up as necessary and insert the dowel again.
Source...