Propagating hydrangeas from cuttings is a dependable method to replicate a favored plant, allowing gardeners to clone shrubs with desirable traits. This technique generates an entirely new, genetically identical specimen. Unlike growing from seed, propagation by cuttings ensures the new plant retains all the characteristics of the original. This process is generally performed using the current season’s growth, which is actively growing but not yet completely hardened.
Clarifying the Leaf-Bud Cutting Method
The method often referred to as “from leaves” is more accurately known as the leaf-bud cutting method, because it requires more than just the leaf blade. This technique utilizes a leaf, its petiole (leaf stem), and a small section of the stem containing an axillary bud. The axillary bud, located where the leaf joins the stem, is the specific tissue that will eventually develop into the new stem and canopy of the plant.
This method is useful for quickly multiplying certain hydrangea varieties, such as Hydrangea macrophylla (bigleaf hydrangea), as it conserves parent plant material. By using only a single node, many new plants can be generated from one stem. The best time to take these “softwood” cuttings is during late spring or early summer, typically between May and mid-July, when the new growth is flexible and snaps easily rather than bending.
Harvesting and Preparing Cuttings
Begin by selecting healthy, non-flowering stems from the parent plant, preferably in the cool, early morning when the plant is fully hydrated. Use a sharp, sterilized blade or pruners to make clean cuts, which minimizes the risk of introducing disease. The cutting should be taken just below a leaf node, the exact point where the leaf attaches to the stem.
Next, remove the lower leaf or leaves, leaving only the top set of leaves on the cutting. Since hydrangeas have large leaves, it is important to reduce the leaf surface area to conserve water and prevent excessive moisture loss. Carefully cut the remaining leaf or leaves in half horizontally, reducing the surface area by about 50%. Finally, dip the cut end of the stem into a rooting hormone powder or gel, ensuring the cut surface and the node area are thoroughly coated to stimulate root development.
Establishing the Rooting Chamber
After preparing the cuttings, they must be immediately placed in a suitable rooting medium to prevent desiccation. An ideal medium provides excellent drainage and aeration while retaining sufficient moisture, such as a mix of peat moss and perlite or coarse sand. Use a pencil or dibber to create a planting hole in the moistened medium before inserting the cutting, which prevents the rooting hormone from being rubbed off.
The environment must maintain high humidity to sustain the cutting until roots can absorb water effectively. This is achieved by creating a rooting chamber, often by covering the pot with a clear plastic bag, dome, or tote. Place the covered cuttings in a location that receives bright, indirect light; direct sunlight can cause the temperature inside the chamber to spike, potentially damaging the cuttings.
Post-Rooting Care and Transplanting
Rooting typically occurs within two to four weeks, but this timeline depends on ambient temperature and humidity levels. Signs of successful rooting include the emergence of new leaves at the axillary bud or a gentle resistance when the cutting is lightly tugged. Once resistance is felt, the new plant is ready to begin the transition to a lower-humidity environment.
This hardening-off process involves gradually exposing the new hydrangea to normal atmospheric conditions over about a week. Start by propping open the plastic cover for a few hours each day, slowly increasing the duration until the covering is removed entirely. After this period, the rooted cutting can be carefully transplanted into a larger pot filled with standard potting mix or directly into a protected garden location. When transplanting, handle the fragile new root system with care to minimize disturbance and ensure continued growth.