Willow cuttings are a popular method for propagating new trees because the wood naturally contains high concentrations of rooting hormones, specifically indolebutyric and salicylic acids. This allows willow (genus Salix) to root easily compared to many other woody plants. While the process is straightforward, the time it takes for a cutting to develop a viable root system varies, but initial root growth typically begins within one to four weeks.
The Typical Rooting Timeline
The first sign of successful rooting often appears quickly, with small white bumps, known as root initials or callus, forming on the submerged portion of the cutting within seven to ten days. This callus is a mass of undifferentiated cells that precedes the emergence of true roots.
True adventitious roots, which are white, thread-like structures, usually begin to stretch out from the cutting within one to two weeks of being placed in water or a moist medium. For the cutting to be ready for transplanting into soil, it needs an established root system, which generally takes about four to six weeks. At this stage, the roots should be firm and several inches long.
Key Factors That Influence Rooting Speed
The speed at which a willow cutting roots depends on environmental conditions, with temperature being a major influence. Root initiation requires adequate warmth, with soil temperatures of at least 50°F (10°C) necessary to stimulate the process. Cold temperatures slow or halt root development, while high temperatures can cause the cutting to dry out before roots form.
Moisture is required, as the cutting must be kept constantly damp to prevent desiccation. The cutting’s age and size also play a role; younger wood, typically one-year-old growth about the thickness of a pencil, roots faster. Some species, such as Weeping Willow (Salix babylonica), root more rapidly than others.
Preparing and Planting Your Willow Cuttings
The best time to take willow cuttings is during the dormant season, from late fall after the leaves drop until early spring before bud break. Selecting healthy, one-year-old wood about 1/2 inch in diameter is recommended. Cuttings should be approximately 8 to 12 inches long, with a slanted cut at the bottom to increase the surface area for water absorption and root emergence.
When planting, ensure that at least two nodes are submerged beneath the rooting medium. Nodes are the small bumps where leaves or buds were attached. Cuttings can be rooted directly in moist soil or a soil-less mix, or started in water. While rooting in water often yields faster initial growth, the resulting roots may struggle when transferred to soil. Direct planting in a well-draining, moisture-retentive medium is a more reliable method for long-term establishment.
Identifying Root Growth and Transplanting
A cutting is successfully rooted and ready for transplanting when the new roots are white, firm, and have reached a length of two to three inches. The emergence of new leaf growth at the top of the cutting also signals success, indicating the plant has established a functional connection between its roots and shoots. Avoid disturbing the cutting too frequently to check for roots, as this can damage the delicate new growth.
Before moving the rooted cutting to its final outdoor location, it should be hardened off by gradually exposing it to outdoor conditions over about a week. This process helps the plant adjust to direct sunlight, wind, and temperature fluctuations, reducing transplant shock. When planting, choose a location that receives full sun and has consistently moist soil, as willows require large amounts of water to thrive.