Detailed Explanation of Dragon Juniper Cultivation Techniques and Maintenance Management Points
Dragon juniper belongs to the Cupressaceae family, genus Juniperus. Aliases: Rraolongbai, Luosibai. It originates from southern Northeast China, North China, as well as Japan, Korea and other places. It is cultivated in cities throughout southern North China and East China. In the same genus, there is Golden Dragon Juniper whose leaves are all scale leaves, with yellow leaves at the branch tips; and Creeping Dragon Juniper which has no upright trunk, with the plant spreading flat on the ground, mostly with needle leaves.
Biological Habits
Dragon juniper belongs to the Cupressaceae family and is a cultivated variety of Chinese juniper. It is an evergreen tree that can reach up to 8 m in height, with a straight trunk and a narrow cylindrical tree shape. Its branchlets twist and extend upward, which is how it got its name. The branchlets are dense, the leaves are densely grown, all being scale leaves. Young leaves are pale yellow-green, turning emerald green when mature. The cones are blue-green with a slightly whitish powdery surface.
Dragon juniper prefers deep, fertile soil and requires good drainage. It dislikes damp and waterlogged conditions, otherwise it will cause yellowing of leaves and poor growth. When young, it grows relatively slowly; after 3-4 years, growth accelerates. After the trunk reaches above 3 m in height, its vigor gradually weakens.
Dragon juniper prefers sunlight. It grows well in places with good drainage and deep soil layers. It has strong drought tolerance. In summer and autumn, as long as the root zone or seedbed is covered, it rarely dies even without watering for drought resistance. However, to promote growth, frequent fertilization and watering can increase its annual growth by up to 50 cm. The main branches of dragon juniper have strong extending ability, but in Jiangnan they do not spread outward but coil upward around the trunk. The lateral branches are closely arranged, and the whole tree resembles two dragons embracing a pillar. Therefore, the lower branches should be properly preserved and must not be casually pruned or damaged, otherwise it will form bare-legged seedlings, greatly damaging the appearance. So generally no pruning is done, and it is allowed to grow naturally.
In addition to the natural conical shape of dragon juniper, some are trained and twisted into animal shapes such as dragons, horses, lions, and elephants. Some are pruned into round ball shapes, drum shapes, or hemispherical shapes, planted singly or in rows, or in groups in courtyards. Some are even planted as hedges, and after shaping and pruning into flat, rounded-ridge forms, they can display their low, full, delicate, and fine characteristics. The lateral branches of dragon juniper twist in a spiral manner around the trunk, making it unique and highly ornamental. It is widely cultivated throughout China.
Cultivation Management
Dragon juniper is customarily propagated asexually. Methods include approach grafting, branch grafting, cuttings, and layering, each with its own advantages. They are described separately as follows:
1. Approach grafting: Approach grafting has a high survival rate and produces seedlings quickly. The disadvantages are limited propagation quantity and relatively troublesome procedures and management. Because the mother tree is tall, operations are even more inconvenient. However, for small-scale propagation, this method can still be used. Rootstocks for approach grafting can be Chinese juniper, Juniperus chinensis var. pendula, Platycladus orientalis, or Chamaecyparis pisifera. It is carried out in March-April, and by August-September the union is fully healed, so it can be cut from the mother plant and transplanted. For specific operations, please refer to the article "Approach Grafting."
2. Early spring branch grafting: In early spring in February, use 2-year-old Platycladus orientalis as the rootstock. Select robust, pest-free 1-2 year old dragon juniper branches as scions, 5-10 cm long. Remove the needles from the lower 2-3 cm. Make a straight cut on one side, 2-3 cm long, and a slanted cut on the opposite side, 2-4 cm long. The rootstock can be cut at the grafting point, then make a straight cut from one side of the cross-section, 2-3 cm long. Note that both cuts should include a small amount of xylem. Then insert the prepared scion into the rootstock, aligning the cambium layers on one side, and tie the union tightly with plastic film. To prevent the scion from losing water and dying before survival, a small plastic bag can be placed over the scion. After about 2 months, if the terminal bud of the scion sprouts, it proves that the wound has healed well. The bag can then be removed and normal management can begin. In addition, during the growing season, bark-stripping and patch grafting can be used. This grafting method also has a very high survival rate.
Propagation Methods
Dragon juniper is a precious garden tree. Its crown is cylindrical, resembling a coiled dragon and shaped like a pagoda. It is suitable for planting around high-rise plazas or for potted arrangement. It has the ability to absorb various harmful gases and has a dust-removal effect. Although dragon juniper can produce seeds, they do not germinate easily. Propagation methods are mostly cuttings and grafting. For graft propagation of dragon juniper, spring is suitable from mid-February to early March, and autumn from late September to early October is also possible. Using 2-year-old Platycladus orientalis as rootstock, the grafting methods include:
1. Ground grafting: The above-ground part of the rootstock should be retained. Remove 3-5 cm of soil from the root collar area. Cut the rootstock to about one-half its depth. Select the middle section of a 2-year-old branch as the scion, about 8 cm long. Remove one-third of the needles at the base. Cut one side into a slope 1.5-2 cm long, and the other side about 0.6 cm. Insert the scion into the rootstock cut, align the cambium layers of both, tie tightly with plastic film, and mound soil 3-5 cm high. Cover with grass to prevent drought, and also set up a frame with a curtain for temporary shade.
2. Digging grafting: After digging up the rootstock, properly trim the roots and branches. The digging grafting method is the same as ground grafting, but after grafting it must be planted promptly, with soil mounded to 3 cm above the top. After grafting, dragon juniper heals and establishes relatively slowly. Spring grafting begins to heal in May, so the rootstock branches and leaves should be gradually pruned. After grafting, in addition to proper shading, preventing dry wind, and maintaining certain moisture, within half a month after grafting, rain must also be prevented from entering. The general survival rate can reach above 75%.
Pest and Disease Control
Dragon juniper has relatively few diseases. In addition to the above-mentioned pear rust, the common one is purple root rot, which easily occurs when the cutting seedbed substrate is unclean or reused. It can be controlled according to the methods described above. A common insect pest is the bagworm moth. It should be controlled by spraying 1000 times diluted 98% trichlorfon crystals in early June before the larvae spread.