Boxwood (Buxus) is a popular ornamental shrub known for its dense, evergreen foliage, often used in formal landscaping and topiary. Propagating new plants from cuttings is the most common method for increasing stock while maintaining the parent plant’s exact characteristics. Success relies on selecting the proper time of year to harvest the material and preparing it correctly. Precise timing ensures the cutting is at the optimal stage of maturity to initiate root growth.
Optimal Timing for Boxwood Cuttings
The most successful propagation of boxwood occurs when the cutting material is at the semi-hardwood stage of growth, typically spanning from late summer through mid-fall (August to October). This window provides the best balance of stem maturity and hormonal activity. The current season’s growth has begun to firm up and develop a slightly woody texture but is not yet fully hardened.
This maturity is favorable because the stems are lignified enough to resist rot and survive the rooting process, yet still possess sufficient physiological activity to form roots. Cuttings taken earlier in the year, during the soft growth stage of spring, are less reliable for this species. Softwood cuttings are prone to wilting and decay before roots can develop due to their high water content.
The wood taken in late summer benefits from warm soil temperatures, which helps stimulate root production. Taking cuttings within this August to October period allows the new root system to begin developing before the plant enters its winter dormancy. This head start is beneficial for the cutting’s survival over the winter and its subsequent growth the following spring. Avoid taking cuttings too late in the fall, as the lack of warmth and light can delay rooting until the next season.
Selecting and Preparing the Cutting Material
After identifying the correct time, select healthy parent material to ensure a strong start for the new plants. Cuttings should be taken from vigorous, disease-free stems of the current season’s growth that have not yet flowered. A length of four to six inches is adequate, allowing sufficient stem material to be placed into the rooting medium.
The cut should be made cleanly just below a node, which is the point on the stem where a leaf or bud is attached. Using a sharp, sterilized knife or pruners is important to avoid crushing the stem tissue, which can impede water uptake and create an entry point for pathogens. The leaves from the lower half must be stripped away to prevent them from rotting when buried in the medium.
Preparation involves treating the cutting with a rooting hormone, which increases the success rate and speed of root initiation. For semi-hardwood boxwood, high concentrations of Indole-3-butyric acid (IBA) are most effective, often in the range of 3,000 to 5,000 parts per million (ppm). To maximize hormone absorption, “wounding” is recommended, where a thin strip of bark is lightly scraped off one side of the bottom inch of the stem before dipping it into the hormone powder or liquid.
Establishing the Cuttings for Rooting
The prepared boxwood cuttings require a specific environment to transition into a rooted plant. A well-draining, low-fertility rooting medium is necessary to prevent waterlogging and discourage rot. A common mixture consists of equal parts coarse perlite and peat moss, which provides aeration and moisture retention.
The cuttings are inserted into the medium deep enough to cover all the defoliated nodes, and the medium should be gently firmed around them to ensure good contact. Creating an environment of high humidity is necessary to prevent the cuttings from desiccating before they can draw water through roots. This is often achieved by placing the pots inside a clear plastic dome or bag to maintain a consistently moist atmosphere.
The rooting area should receive bright, indirect light, avoiding direct sunlight which can overheat the enclosed space and scorch the foliage. Maintaining a consistent temperature, ideally between 65 and 75 degrees Fahrenheit, encourages the physiological processes for root formation. Initial root development typically begins within several weeks, though late-season cuttings may not exhibit rooting until the following spring.