The aromatic eucalyptus, a popular fragrant evergreen, can be propagated through cuttings to clone a tree with desirable traits. This method allows gardeners to replicate the exact qualities of a parent plant, unlike growing from seed, which introduces genetic variability. Successful propagation requires precise preparation and selection of the rooting medium.
Essential Steps for Cutting Preparation
Selecting the correct material from the parent plant is essential for successful propagation. Cuttings should be taken from semi-hardwood stems, which are current season’s growth that has begun to firm but is not yet fully woody. The ideal time to take these cuttings is during the late spring or early summer when the plant is actively growing.
Each cutting should measure approximately four to six inches long and include at least two to three leaf nodes, where root development is most likely to occur. Using sterilized pruning shears, make a clean, angled cut just below a node to maximize the surface area for uptake. To prevent rot and reduce moisture loss, strip the leaves from the lower half of the stem, leaving only a few leaves at the top.
Assessing Water Propagation
Rooting eucalyptus in a water vessel is a common question, as many household plants root successfully this way. While it is technically possible to initiate root growth in water for some species, it is generally a difficult and low-success method for eucalyptus. The main challenge is the plant’s high susceptibility to fungal and bacterial infections when submerged.
If attempting water propagation, place the prepared cutting in a clear glass vessel filled with clean, non-chlorinated water. Place the vessel in a location receiving bright, indirect light, avoiding direct sun that can overheat the water. To minimize rot and ensure adequate oxygenation, the water must be changed every few days. The roots that form in water are often weaker and more brittle than those developed in a solid medium, making the eventual transition to soil stressful for the young plant.
Success can depend heavily on the specific eucalyptus variety and controlled conditions, as some studies have shown high rooting percentages using water culture techniques. However, for the average gardener, the primary concern remains the vulnerability of the cutting’s submerged end to anaerobic breakdown. Rooting in water is not the recommended or most reliable technique.
The Reliable Alternative: Medium Propagation
The preferred and significantly more reliable method for propagating eucalyptus cuttings involves planting them directly into a sterile, well-draining rooting medium. This environment provides the necessary balance of moisture, aeration, and support. An ideal mixture often consists of a blend of materials like perlite, coarse sand, or pine bark mixed with peat moss or compost.
Before planting, the prepared cutting should be dipped into a rooting hormone, typically a powder or gel containing Indole-3-butyric acid (IBA). This step is a significant factor in promoting root initiation, especially for plants that are naturally difficult to root. The hormone stimulates the cells at the cut surface to differentiate into root tissue.
Insert the hormone-treated cutting into the prepared medium deep enough to stand upright, ensuring at least one node is buried. After planting, the cuttings require a high-humidity environment to reduce transpiration stress while roots are forming. Covering the container with a clear plastic dome or a plastic bag creates a mini-greenhouse effect, maintaining humidity and a warm temperature, ideally between 65 and 75 degrees Fahrenheit. This setting encourages robust root development, which typically begins within four to eight weeks.
Transitioning Rooted Cuttings
The first sign of successful rooting is often new leaf growth on the cutting. In a solid medium, resistance when gently tugging indicates that roots have anchored it. Once the root system is established—meaning roots are visible through the drainage holes or are a few inches long—the young plant must be prepared for its permanent environment.
The process of moving the rooted cutting requires a period known as “hardening off.” This gradual acclimation transitions the plant from the protected, high-humidity environment to normal atmospheric conditions. Over about two weeks, the plant should be exposed incrementally to lower humidity, direct sunlight, and wind.
Start by removing the humidity cover for a few hours each day, slowly increasing the duration of exposure. Once fully hardened, transplant the cutting into a larger pot using well-drained soil, such as a standard potting mix amended with perlite. Initial watering should be thorough, but subsequent watering should allow the soil to dry slightly between sessions, as eucalyptus is prone to root rot if overwatered.