The Fatsia japonica, commonly known as the Japanese Aralia, is an attractive evergreen shrub prized for its large, deeply lobed leaves that bring a bold, architectural feel to a garden or home. Propagation is the simple process of creating new plants from an existing specimen, allowing you to multiply this decorative plant. Successful propagation involves careful timing, the right tools, and understanding the plant’s growth habits.
Essential Preparations and Timing
The ideal time for propagation depends on the method selected, though spring and summer are the most active growing periods. For stem cuttings, aim for late spring through late summer when the plant is actively growing and the stems are semi-hardwood. Separating offsets can be performed at any time, but is often easiest in the spring when the plant is preparing for its main growth push.
Preparation involves gathering the necessary tools and selecting a suitable rooting medium. All cutting tools, such as knives or pruners, must be clean and sterilized to prevent the spread of disease. A light, well-draining, and sterile rooting medium is essential for cuttings; a mixture of equal parts perlite and peat moss or sand and peat moss works well. Maintaining a consistent temperature between 15°C and 20°C (60°F and 68°F) encourages root development.
Method 1: Rooting Stem Cuttings
Propagating Fatsia japonica from stem cuttings requires selecting semi-hardwood material—young stem growth that has just begun to firm up. Choose healthy, non-flowering stems and use a sharp, sterilized blade to take a cutting 4 to 6 inches long. Make the final cut just below a leaf node, as hormones naturally concentrate there and new roots are most likely to form.
To minimize moisture loss, carefully remove the lower leaves, leaving only a few small leaves at the tip of the cutting. Applying a powdered or gel rooting hormone to the freshly cut end stimulates faster root growth. Insert the treated end of the cutting about two inches deep into the prepared rooting medium, ensuring the medium is moist but not saturated.
After planting, creating a high-humidity environment is necessary for the cutting’s survival until roots form. This is accomplished by placing the pot inside a clear plastic bag or under a humidity dome to create a small greenhouse effect. Place the covered cutting in a location that receives bright, indirect light, avoiding direct sunlight which can easily overheat the environment. Roots generally begin to develop within one to two months.
Method 2: Separating Offsets and Suckers
Separating the small shoots that emerge from the base, known as offsets or suckers, is a fast and reliable propagation method for mature Fatsia japonica. These new plants often come with their own root systems. Identify a viable offset that has a few leaves and appears connected to the main plant’s roots. Gently dig around the base of the mother plant to expose the root crown and the offset’s connection point.
Use a clean, sharp knife or spade to sever the offset from the parent plant, ensuring the separated section retains as much root mass as possible. A clean separation minimizes damage to both the new plant and the mature specimen. The separated young plant should be potted immediately into standard, well-draining potting soil.
Plant the offset at the same soil level it was growing at previously, firming the soil gently around the roots. This method eliminates the need for rooting hormone or a humid environment since the plant is already established. Water the newly potted offset thoroughly to settle the soil and place it in a shaded or partially shaded location to recover from transplant shock.
Establishing and Transplanting Young Plants
The first indication of successful rooting in stem cuttings is new vegetative growth, but a more reliable test is a gentle tug on the stem. If the cutting offers resistance, new roots have anchored it into the soil. Once rooted or successfully separated, the young plant must be gradually introduced to normal environmental conditions through a process called hardening off.
For cuttings under a humidity dome, slowly reduce the humidity over several days by opening the plastic cover for progressively longer periods. This transition prevents the young leaves from wilting when exposed to drier air. Maintain consistent moisture in the potting medium, allowing the top layer of soil to dry slightly between waterings, but never allowing the roots to dry out completely.
Hold off on fertilizing until the young plant is actively growing and fully established. When the roots begin to fill the current container, indicated by roots emerging from the drainage holes, it is time to move the plant into a larger pot or its permanent location. Transplanting is best done in the spring, using fertile, well-draining soil and ensuring the plant receives bright, indirect light.