Ligustrum Bonsai Tree Care Guide
Ligustrum is a genus made up of 40-50 species of shrubs and small trees, ranging from deciduous to semi-evergreen to evergreen. They are native to a variety of locations, including thickets and woodland areas of Asia, the Himalayas, Australia, North Africa, and Europe. Commonly known as privet, these species are often used for domestic hedges, but in their natural environment grow to a height of 6-45 feet depending upon the type. Interestingly, the collection and cultivation of privet has been banned in New Zealand due to its propensity to cause asthma and eczema in those with sensitivities.
The opposite, ovate leaves tend to be glossy, dark green, and range from 1-2" long in many species, up to 4" in the Japanese Privet, Ligustrum japonica. Some varieties used in bonsai have lighter green leaves, such as L. Sinense. The bark usually matures to a smooth finish and many varieties have the ability to form nice thick trunks that are so attractive to enthusiasts. This shrub may produce sprays of tiny white flowers, giving way to dark shiny berries (these are moderately poisonous so care should be taken around children and pets).
Privet plants are hardy and can tolerate temperatures as low as 20° F but should be brought inside if it becomes colder than that. They may be kept as an indoor tree as long as the humidity is kept high enough (a humidity tray from can help with this) and the tree is provided with enough light.
The important thing to remember is that if a tree has been kept inside, do not suddenly put it outside during the winter. In order to acclimate, it must be allowed to go through the natural weather changes that fall provides. All bonsai should have root protection in temperatures below freezing, and some privet varieties will lose leaves in cold weather but will grow back vigorously come spring.
Improper watering kills more bonsai than any other cause. While Ligustrum is tolerant of overwatering, it will begin to wilt if it stays too dry for too long. Check the soil every day, preferably twice a day in the heat of summer. One way to water thoroughly is to dip the pot into a basin with a couple inches of water in it; allow it to get completely soaked then lift and allow the excess to run out the drainage holes.
Once new growth begins appearing in the spring you can fertilize your bonsai on a bi-weekly schedule, using an organic liquid feed, or a regular plant fertilizer at half strength. Continue this routine through the growing season, decreasing to once a month feeding in winter.
Styles – privet takes well to informal upright, slanting, multiple trunk, and group plantings.
Wounds from pruning will heal faster if this task is carried out in spring or summer. This tree is well-suited to training by wiring or clip and grow. Long shoots with 8-10 sets of leaves will form in the growing season. If you do not want these to turn into branches, clip them back to one or two sets. Privet grows very quickly and densely which makes frequent trimming a necessity. In addition, the tree is a vigorous producer of suckers which will need to be removed from the base so that they don't divert energy away from the rest of the tree.
Wiring is best done right after a branch lignifies. New growth tends to harden fast in these species so keep an eye on any new growth that you might want to use wire on. Loosen the wire when necessary to avoid cutting in, as stated above this tree grows at a brisk clip during the growing season.
Ligustrum may be propagated by seeds in the spring, or softwood cuttings in spring and hardwood cuttings in fall. For softwood cuttings, take a length of shoot that includes new leaves and some that are more developed. Keep in a moist soil mixture until roots take form. The new plant may be ready to be transplanted to a bonsai pot by late spring.
Hardwood cuttings should be taken in late fall to winter, after the growing season is over. Take a cutting with a heel and place heel side down in moist soil. Keep the cutting indoors until spring when the root system will be developed enough to sustain the new bonsai.
Younger privet should be repotted each year in the spring. Older trees can be done every other year. This tree produces a fibrous, dense root system that responds well to root pruning. Transplant into a standard, well-draining bonsai soil.
Insects/Pests & Diseases
This plant can be vulnerable to typical bonsai issues like aphids, scale, and wilt. Inspect your tree often for any signs of health problems like visible insects or black spots.