Here are some helpful tips:

Take cuttings from plants growing at peak growth periods, like spring or fall. The plants have a balance of hormones that promote quick tissue growth, including roots.

You will get best results by using firm green stems with at least one node under an airy sterile medium (not garden dirt or water). If you have ever prepared asparagus by bending the stalks until they snap and discarding the lower, tough piece, you can figure out where the best part of the cutting is to be in the medium. The easy to bend parts must not be placed in the medium since they will rot quickly and not root. The firm stem without bark is optimal for forming roots. The stem with bark will have a harder time forcing roots through.

The purpose of the node underground is to provide new underground sprouts to replace an old or broken leader. This can become a self-propagating process, leading to a vigorous clump.