Layering is a method that is used to multiply plants that have stems that lay along the ground or spread along the ground before bending upward. You may see that some stems have already sent roots into the ground. These can be cut apart with a sharp knife without disturbing the mother plant. The new sections are then potted up and grown on or planted out immediately if the roots are sufficiently developed for the size of the section. If there are no roots on the spreading stems, remove some leaves and mound good soil around them. Sometimes you can gently bend a stem to the ground, remove leaves where it touches the ground and dust with rooting powder. It may be necessary to pin the stem with a bent wire to maintain close contact with the soil. Mound some good soil over the contact point. After several weeks, new roots and top growth will occur and the section can be removed and treated as a division. The Dasanthera section species, Ericopsis section species and Penstemon pinifolius are often propagated this way.
A form of layering takes place naturally on Penstemon ambiguous, but the new growth begins on underground stems or roots that cannot be seen. The new green stems will be several inches from the mother plant. When they have become firm in late August or September, depending on when the summer rains occurred, a sharp, deep cut with a spade will separate the new plant and it can be planted in a new location or potted up to develop more roots if necessary.
Penstemon californicus sometimes does self-layering, where branches root when touching the soil.