How to source materials and cultivate Chinese juniper bonsai? A detailed guide to practical methods
Chinese juniper (Juniperus chinensis), native to China, has a slender, pointed tree form, cylindrical in shape, rising straight upward, with new branches growing around the trunk, resembling a green dragon coiled around a pillar, hence the name "dragon juniper." Its leaves are small and dense, emerald green, scale-like and alternately arranged, with spherical blue fruits that remain unchanged through the four seasons. It is a relatively superior and high-quality ornamental tree for parks and courtyards.
Chinese juniper is usually propagated by cuttings, grafting and other methods. Cuttings are generally taken in April. For cuttings, it is best to select a mother tree about 10 years old and cut lateral branches from the middle and upper outer part of the crown. Branches from young trees are not suitable because they grow insufficiently and have a low rooting and survival rate. Cuttings should be 12-20 cm long; remove the small lateral branches from the part that will go into the soil, dip the base into a 500PPM indoleacetic acid solution for about 1 minute, then insert immediately after removal, with the insertion depth about 1B3 or 1B4. After inserting, press the soil firm with your fingers so that the soil tightly contacts the cutting, water thoroughly, and then build a shade frame. The seedbed soil is best as sandy loam or leaf mold, loose and fertile, suitable for growth. Generally, fast cuttings root in about 50 days, and the survival rate can reach over 80%.
For grafting, Chinese arborvitae (Platycladus orientalis) or Chinese juniper is commonly used as rootstock, with Chinese arborvitae being the best. The Chinese arborvitae seedling should not be too large; generally two-year-old seedlings are best. In early spring, use the side veneer grafting method. There is no need to cut off the upper part of the rootstock; instead, make a diagonal cut downward on the lower part of the trunk near the ground, then cut the tip of a Chinese juniper lateral branch, about 20 cm long, sharpen the base into a slant, insert it into the cut in the rootstock, tie it tightly with plastic tape, and bury the grafted scion in the soil, leaving about one-half of the tip exposed. After the graft has completely taken, cut away the Chinese arborvitae tree, then manage normally. After two years, it can be transplanted to make a small bonsai.
For grafting propagation, the side veneer method should be used. Usually, 3-year-old Chinese arborvitae seedlings are used as rootstock, and 2-year-old Chinese juniper branch tips are used as scions. Side veneer grafting is carried out in April in spring, and after grafting, soil is mounded up to the graft union. Stumps can be selected directly from the nursery. Generally, the material for making large and medium-sized Chinese juniper bonsai is a semi-formed stump about ten years old purchased from a nursery, with a diameter of about 7cm—12cm. Such stump material takes shape quickly, and the transition between branches and trunk is natural.
After survival, in April of the following year, first cut off the upper branches and leaves of the rootstock, then cut off the rootstock above the union flush with the joint. Those that fail to take can be grafted again. As long as the technique is appropriate, the survival rate can reach over 90%. Grafted seedlings are easy to manage and grow relatively fast, making them suitable for making Chinese juniper bonsai.