Boxwood shrubs (Buxus species) are a preferred choice for formal hedges and garden accents due to their dense, evergreen foliage. While they can be grown from seed, propagation via stem cuttings is the most common and effective asexual method used by gardeners. This technique creates genetically identical copies of the parent plant, allowing for the rapid and economical production of many new plants from a single established specimen.
Selecting the Best Time and Material
The success of boxwood propagation depends on using the correct material at the optimal time. The best window for taking cuttings is in late summer, typically between July and August, when the current-year growth has reached the semi-hardwood stage. Semi-hardwood growth is firm and slightly woody at the base but remains flexible and green at the tip.
Select healthy, vigorous stems from the outer growth of the shrub, ensuring they are free from disease or pest damage. The ideal length for a boxwood cutting is between four and six inches. Taking cuttings early in the morning is recommended, as fully hydrated stems minimize water loss during preparation.
Preparing the Cuttings for Planting
Once the material is selected, immediate preparation is necessary to encourage root formation. Using a sharp, sterilized knife or pruners, make a clean cut just below a leaf node, an area naturally concentrated with root-producing cells. While some prefer a “heel cutting” that includes a sliver of older wood, a clean node cut is also highly effective.
Strip the foliage from the lower half of the cutting, leaving only two to four leaves at the top. Removing these lower leaves prevents rotting beneath the soil and minimizes water loss through transpiration. Applying a rooting hormone significantly increases the speed and success rate of rooting. Dip the cut end into a powdered or gel hormone, ensuring a light, even coating, and tap off any excess to prevent chemical burn.
Setting Up the Rooting Environment
The environment where the cuttings are placed must provide specific conditions for root development. A sterile, well-draining rooting medium is preferred over standard potting soil. A common and effective mix is a 50/50 blend of peat moss and perlite or coarse sand, which offers excellent aeration and drainage. Use a container with drainage holes, and pre-moisten the medium before inserting the cuttings.
The cuttings require bright, indirect light to photosynthesize without being scorched. Maintaining high humidity is necessary for survival until roots form, as the cuttings cannot yet take up water efficiently. Achieve this by covering the container with a clear plastic bag or a humidity dome, creating a miniature greenhouse effect. The medium should be kept consistently moist, but never waterlogged, and the cover should be opened occasionally for air exchange and to prevent fungal growth.
Transitioning Cuttings to the Garden
After six to twelve weeks, the cuttings should have developed a viable root system, confirmed by a gentle tug on the stem that meets resistance. Once rooted, the young plants must undergo “hardening off” before being permanently planted in the ground. This process is a gradual introduction to lower humidity, direct sunlight, and wind to prevent transplant shock.
The hardening off process typically spans one to two weeks. Begin by placing the rooted cuttings outdoors in a shaded, sheltered spot for one hour on the first day. Each subsequent day, increase the time outdoors and slowly expose the cuttings to more direct sunlight and wind.
Because the new boxwoods are still small, they require protection during their first winter, especially in colder climates. They can be kept in a sheltered location, like a cold frame or unheated garage, to guard against severe temperature fluctuations. Permanent transplanting into the garden is best done the following spring or fall, into well-draining soil. Ensure they are watered thoroughly after planting to help them establish.