Detailed Guide to the Latest Care and Management Methods for Chinese Juniper Bonsai
Chinese juniper (Juniperus chinensis), an evergreen tree, up to 20 m tall, 3.5 m in diameter at breast height, with a crown of spire or conical shape, and broadly ovate in old trees. Leaves of 2 types: on young trees or on vigorously growing adventitious shoots at the base they are mostly triangular-subulate, in whorls of 3, with a joint at the base extending downward; on old trees they are mostly scale-like, opposite, closely appressed to the twigs; there are also plants that remain entirely subulate-leaved from youth. Flowers dioecious; male cones formed in autumn and opening the following year, yellow; female cones small; the cone matures the following year, berry-like and indehiscent, coated with white powder.
Chinese juniper is widely distributed, from Inner Mongolia and Liaoning in the north, south to northwestern Guangdong and Guangxi, west to Sichuan and Xizang, and east to East China, and is cultivated everywhere. Chinese juniper likes light, tolerates slight shade and drought and poor soil, and can grow in acidic, neutral and calcareous soils; it is a common greening tree species on limestone hills.
Watering: Chinese juniper is drought-tolerant, so do not keep it too wet; water only when dry, following the principle of dry-wet alternation. In the plum rain season, take care that water does not accumulate in the pot; in high summer temperatures, water in the morning and evening and just keep the potting soil moist; frequent misting of the foliage keeps the leaves emerald green.
Fertilizing: Chinese juniper bonsai should not be fertilized heavily, lest excessive growth spoil the beauty of its shape. Each spring, from March to May, apply dilute well-rotted cake fertilizer water or organic fertilizer 2 to 3 times, and in autumn apply it 1 to 2 times, to keep the branches and leaves fresh green and dense and the growth robust.
Pruning: For a shaped Chinese juniper bonsai, mainly pinch out the growing tips; for vigorous shoots, nip the tips and cut off the apex to encourage side branches. During the period of vigorous growth, pay special attention to pinching and nipping in good time to keep the crown dense and the form beautiful.
Repotting: Chinese juniper bonsai grows slowly, so it can be repotted once every 3 to 4 years, preferably in March to April in spring. When repotting, part of the old roots may be pruned away as appropriate, half of the old soil replaced, and fertile, loose potting soil added, to promote the growth and development of new roots. In tall, deep pots, take care to place a layer of coarse sand and broken tile pieces at the bottom to help drainage.
Control of Chinese juniper rust:
1. Symptoms: Chinese juniper rust damages the needles and young twigs of Chinese juniper, at first as yellow spots, which later swell, break through the epidermis and expose reddish-brown conical or cockscomb-like bodies, single or several joined together, which are the telial horns. After spring rain, they gelatinize on contact with water into orange-yellow flower-like gelatinous masses, and the teliospores are on the surface of these gelatinous masses.
2. Occurrence characteristics: The mycelium overwinters on Chinese juniper; the following spring it produces telial horns, which germinate on contact with rain and produce basidiospores that are spread by wind. In warm, rainy years in spring, the disease is severe.
3. Control methods: In winter, cut off the heavily diseased branches on Chinese juniper. In October to November, spray Chinese juniper with a mixture of 0.3% sodium pentachlorophenate and 1 degree Baume lime sulfur, which can prevent infection by rust spores. In mid-to-late March, before the teliospores germinate, spray 1 to 2 degrees Baume lime sulfur or an equal-amount 160 to 200 degree Baume Bordeaux mixture 2 to 3 times, once every 7 to 10 days.