Weeping cherry trees, often cultivars of the Prunus species such as ‘Pendula’, are highly valued for their dramatic, cascading branches and profuse spring blossoms. Propagating these ornamental trees allows gardeners to replicate their unique traits, which cannot be reliably achieved through seed alone. Successful propagation requires a specific understanding of plant biology and the choice between two distinct methods: rooting a simple cutting or performing a specialized graft.
Understanding Weeping Cherry Structure
The iconic form of a weeping cherry is typically a composite of two different plants joined together, known as a graft. The lower section is the rootstock, which provides the hardy root system and the straight, upright trunk. This is often a vigorous, non-weeping variety, like Mazzard (Prunus avium), chosen for its disease resistance and soil adaptability.
The upper section is the scion, which is the weeping cultivar responsible for the characteristic flowering and drooping branches. The union is usually visible as a slight bulge or scar on the trunk where the weeping branches begin. Propagating from seed is unreliable because the offspring will not possess the exact characteristics of the parent cultivar, often reverting to the rootstock’s traits or producing a non-weeping variant.
Propagation via Softwood Cuttings
Propagating a weeping cherry from a softwood cutting is the most accessible method for the home gardener, though the resulting plant will lack the tall, straight trunk of a grafted tree. Cuttings are taken from the current season’s growth in late spring or early summer, when the wood is flexible but firming up. A healthy cutting should be four to six inches long, taken from the tip of a vigorous branch, and severed cleanly just below a leaf node.
Preparation involves stripping the leaves from the lower one-third to two-thirds of the cutting to expose the nodes where roots will form. To encourage root development, the cut end is dipped into a rooting hormone, ideally one containing Indole-3-butyric acid (IBA). This hormone stimulates root cell division.
The prepared cutting is then inserted into a sterile, well-draining rooting medium, such as a mix of two parts coarse sand to one part peat moss or coir. The environment must be maintained with high humidity and consistent moisture, achieved by placing the potted cutting in a cold frame or covering it with a clear plastic dome. Consistent misting helps prevent desiccation while roots are forming.
Rooting typically occurs within a month, but the cutting should grow until the roots fill the container before transplanting. A tree grown this way will grow as a weeping shrub unless it is carefully staked and trained upright.
The Grafting Method
Grafting is the technique used by commercial nurseries to produce the classic weeping cherry form, ensuring the tree maintains its full height and weeping characteristic. This method involves physically joining a scion (the weeping wood) onto a compatible rootstock to create a single plant. The ideal timing for grafting is generally in the late winter to early spring, just before the rootstock buds begin to swell.
Alternatively, a technique called T-budding can be performed during the summer months, typically in August, when the bark easily separates from the wood. The process requires a sharp, sanitized knife to make precise cuts that ensure the cambium layers—the thin, green, growing tissue beneath the bark of both the scion and the rootstock—align perfectly.
This alignment is the most important step, as it allows the vascular systems of the two plants to fuse and form a successful union. Common grafting techniques include the whip-and-tongue graft for similarly sized wood or the cleft graft for inserting the scion into a larger rootstock.
After positioning the scion, the graft union must be tightly wrapped with grafting tape or rubber bands. Grafting wax or sealant is then applied over all exposed cuts, including the tip of the scion, to prevent water loss and protect the tissue from disease. The resulting tree will have the hardiness and straight trunk of the rootstock with the desired weeping branches of the scion, faithfully replicating the original cultivar.
Post-Propagation Care and Transplanting
Once a cutting has rooted or a graft has healed, the young tree requires a careful transition to its permanent environment.
Hardening Off
A newly rooted cutting or healed graft must be “hardened off” by gradually introducing it to outdoor conditions. Start with a week in light shade before moving it to a location with direct sunlight. This process prepares the young plant to withstand the elements of the garden.
Container Care
During the first growing season, keep the young tree in a container and monitor it for consistent moisture, preventing the soil from becoming completely dry or waterlogged. Initial fertilization should be light, focusing on balanced nutrients to support root and shoot growth. The optimal time for transplanting the tree into the garden soil is the following spring, when the tree is dormant but before new growth begins.
Establishment and Maintenance
Protecting the young plant is important during its first year in the ground, ensuring it is sheltered from strong winds and severe winter conditions. Any shoots that emerge from the rootstock below the graft union must be promptly removed. These shoots are from the non-weeping variety and will compete with the desired weeping scion. Continued vigilance against pests and disease, along with appropriate watering, ensures the newly propagated cherry establishes itself successfully.