Cancel. The best way to root a Knock Out rose clipping is to dip the end of the branch into honey and plant it in very moist soil. Get a clipping of a Knock Out rose to propagate with helpful information from a sustainable gardener in this free video on roses.Part of the Video Series: Rose Gardening.1  How to Prune Desert Roses.ut it's easy to root a Knockout Rose and once you've got some roots set whether it's in a cup or it's in a container, you can turn around and transplant it into the ground and enjoy them for many years to come.