Morus alba
Native to China, the Morus alba, or white mulberry, is renowned for its broad, vibrant leaves and the silk-producing larvae it hosts, which feed on its leaves. Caring for a white mulberry bonsai offers an engaging blend of horticultural challenge and artistic expression. Known for its resilience and attractive foliage, the white mulberry is an excellent bonsai subject due to its adaptable nature and aesthetic appeal.
Bonsai Styles and Sizes
White mulberry bonsai can be trained in several styles, including Formal Upright (Chokkan), Informal Upright (Moyogi), and even Cascade (Kengai). Each style can be achieved with careful training and pruning. Regarding size, mulberry bonsais are typically most successful in larger forms such as Chu (up to 40 cm tall) and Dai (above 60 cm tall), allowing for a robust display of their natural characteristics.
Light Requirements
Optimal Exposure: White mulberry bonsai trees perform best with full sunlight, receiving at least six hours of direct light daily. Ideally, these bonsai should be placed outdoors to benefit fully from natural sunlight, which promotes vigorous growth and robust health.
Seasonal Adjustments: If temperatures are likely to be above 30C, it is best to provide shade during the summer months to prevent leaf scorch. In winter, ensure the bonsai still accesses ample light, which might mean relocating it to a sunnier indoor spot if temperatures drop significantly.
Watering Techniques
Regular Watering: Morus alba bonsai requires consistent moisture. Ensure the plant is watered thoroughly when the top inch of soil feels dry. Avoid complete drying out of the soil, as this can stress the tree.
Seasonal Watering: Reduce the watering frequency during winter when the tree is dormant. Nevertheless, the soil should never be allowed to dry out completely. Monitoring the soil’s moisture level is crucial, especially during seasonal transitions.
Soil and Fertilisation
Soil Composition: A well-draining granular bonsai soil mix is vital. It typically comprises 1/3 organic matter, like pine bark, fir bark, coco peat, and coir, and 2/3 inorganic matter, pumice, lava rock, or fine gravel. Granular sizes between 3mm and 9mm ensure adequate drainage and aeration, which is essential for healthy root development.
Fertilisation Schedule: Apply a balanced organic bonsai fertiliser monthly during the growing season. Stop fertilising in late autumn and throughout winter as the tree enters its resting phase.
Pruning and Shaping
Structural Pruning: Conduct major structural pruning in late winter, ahead of the spring growth spurt. This involves removing dead or overcrowded branches to enhance light penetration and air circulation within the canopy.
Maintenance Pruning: Pinch back new growth regularly during the growing season to maintain your desired shape and promote a denser foliage canopy.
Wiring Techniques: The branches of Morus alba are relatively pliable, making them suitable for shaping with bonsai wiring techniques. Apply wiring carefully to avoid damaging the bark, and ensure wires are removed before they begin to cut into the wood.
Repotting Essentials
Frequency of Repotting: Young trees should be repotted every two years, while older, more mature specimens may be repotted every three to five years. Regular repotting helps control root growth and rejuvenates the soil.
Best Practices: Repotting is best done in early spring. Gently remove the tree from its pot, trim the outer roots cautiously, and replant using fresh bonsai soil, ensuring the tree sits at its original depth.
Pest and Disease Management
Common Pests: Watch for pests such as aphids and spider mites. Per product guidelines, these can generally be controlled with insecticidal soap or neem oil.
Disease Prevention: Fungal diseases are a potential concern, particularly in humid conditions or if the foliage remains too moist. To minimise disease risk, promote good air circulation and avoid watering the leaves directly.
Propagation
Seed Propagation: White mulberry seeds can be sown in sterile soil, ideally in the autumn. They require cold stratification to germinate, which can be simulated by placing seeded pots in a refrigerator for about a month before moving them to a warmer environment.
Cuttings: Softwood cuttings taken in spring or early summer root the best. Plant the cuttings in a moist, well-draining mix, keeping them at a consistent temperature and humidity level until they root.