To propagate a Knock Out Rose, the best method is to use clippings. When done properly, a clipping can be transformed into a brand new plant in a matter of weeks, reducing the time it takes for a new plant to grow.
Step 1 - Cut Clippings
Remove a branch from a Knock Out Rose. Use the top eight inches of the branch, and remove all but two leaves. On the bottom of the clipping, strip the bark off the first two to three inches. Stripping the bark makes it easier for the plant to absorb nutrients from the soil and helps give it strength to put out new roots.
Step 2 - Prepare Soil
To start a new plant from a clipping, you need the most fertile soil available. Use potting soil, or a mixture of sifted compost and sand. Before trying to start a clipping, dampen the soil and loosen it up. Insert the clipping into the soil at a depth of around three to four inches.
Step 3 - Transplant
When the rose bush has put out roots and new leaves, you will want to transplant it to a permanent location. Dig up the entire root ball, with the soil, and move it to the new location. Place the ball in the hole and fill the remaining area, if any, with compost.