Layering Plants for New Growth
Many shrubs and climbers will naturally develop new roots on low branches if these come in contact with the ground or are buried for any length of time. You can use this phenomenon to produce new plants. Known as layering, it is a particularly attractive method, because the stem used is left attached to the parent plant until it has rooted, so nothing is lost if the attempt fails. This is a useful way to fill a low gap in a mature hedge.
How Layering Works
You can simply bury a stem to exclude light and it might start to root, but the chances of success are often increased by cutting or twisting it to damage some of the tissues. This interrupts the normal flow of hormones and other sap-borne chemicals, encouraging them to become concentrated at the injury site and stimulate root formation. The section of stem beyond the wound will become slightly water-stressed—this also promotes root growth as the plant struggles to survive. Applying a rooting hormone powder or solution to the wound further accelerates the process. Rooting takes a variable amount of time, depending on the species and when you layer the stems: do it in early spring and most layers will have rooted by the fall.
Types of Layering
- Simple layering involves burying a single shoot until it takes root, then severing it in order for a new plant to establish itself.
- Serpentine layering involves pegging down the stems of climbers like clematis, honeysuckle, vines, and wisteria a few times between leaves to produce new plants. Make several wounds along a young stem, each behind a leaf joint or bud. Peg down the wounded sections, leaving the stem between exposed to the light. Roots will form on the buried wounds, while buds on the exposed sections will develop into new shoots. When well-rooted, separate and transplant sections.
- Tip layering is used for blackberries, brambles, and other Rubus that naturally produce roots from their stem tips. It should be carried out in summer.
- Mound layering is also known as “stooling.” In spring, soil is mounded up around the crown of low-growing shrubs such as heathers, rosemary, thyme, and lavender so that they are half-covered. The stems will start to develop roots and can be uncovered, cut off, and transplanted in late summer or fall.