Wax-leaf Privet (Ligustrum japonicum)

Amur, Common Privet, Curlyleaf Ligustrum, Japanese Privet, Privet, Wax-leaf Privet

One of the best plants for hedges is the Japanese Privet, botanical name Ligustrum japonicum. These evergreens produce dense, shiny, dark green foliage and sweetly fragrant white flowers in spring. This plant is a favorite for anyone that is looking to add an attractive, evergreen privacy screen so that they can block unwanted views in style. These are also an excellent shrub for topiaries to create formal and fanciful gardens. Don’t let a lack of space keep you from adding a splash of green to your property – you can also use them as a small tree that can fit in any size yard.

I. Appearance and Characteristics 

Ligustrum japonicum, known as wax-leaf privet or Japanese privet (Japanese: ネズミモチ) is a species of Ligustrum (privet) native to central and southern Japan (Honshū, Shikoku, Kyūshū, Okinawa) and Korea. It is widely cultivated in other regions, and is naturalized in California and in the southeastern United States from Texas to Virginia.

L. japonicum is an evergreen shrub or small tree growing to 2–5 meters (6 ft 7 in – 16 ft 5 in)—rarely 6 meters (20 ft)—tall, with smooth, pale gray-brown bark on the stems. The leaves are opposite, 5–10 cm long and 2–5 cm broad, glossy dark green above, paler glaucous to yellowish green below, thick and leathery textured, and with an entire margin. The flowers are white, with a four-lobed corolla 5–6 mm long; they are borne in clusters 7–15 cm long in early summer. 

The fruit is an oval drupe, 10 mm long, ripening purple-black with a glaucous waxy bloom in early winter; in Japan they are popularly likened to mouse or rat droppings. 

The species is closely related to the Chinese Ligustrum lucidum, differing in its smaller size (L. lucidum making a tree to over 10 m tall), and elongated oval (not subglobose) fruit. Flowering occurs from July to October and fruiting occurs in autumn while reproducing asexually. The plant grows in sun or shade, damp, disturbed, or undisturbed areas, commonly found in floodplain forests, wetlands, and pine flatwoods. Exotic plant invasion is considered one of the main causes of the degradation of ecosystems and loss of biodiversity globally. Japanese Privet is native to Japan and Eastern Asia and was introduced to the United States from Japan and Korea in 1845. 

Ligustrum japonicum is commonly used as ornamental in many parts of the world. They are valued by their evergreen leaves, white flowers, adaptability to different ranges of landscape conditions, pruning, resistance to diseases, and wide availability. Some Ligustrum species have escaped cultivation and become naturalized in natural areas. For example, sixteen countries report the naturalization of Chinese privet. In the United States, Chinese privet has been established in 20 states and it’s considered invasive.

Japanese privet has toxic properties which can harm humans if parts of this plant are ingested. Symptoms are typically moderate, although they can become severe or even result in death in the worst cases. The ill effects are caused by the toxic compounds contained in the fruits and leaves. Symptoms induced by these compounds include stomachache, headache, nausea, diarrhea, vomiting, weakness, low blood pressure, and clammy skin. As a popular ornamental plant in gardens and yards, these plants might easily be within the reach of children, who may ingest parts of the plant without being aware of the potential danger.

II. How to Grow and Care

Sunlight

Grow Japanese privet where it will receive full sun. Provide light shade if growing it in a hot inland location. Avoid growing large, overhanging shrubbery or trees near Japanese privet because dim lighting conditions will cause leggy growth.

Temperature

Japanese privet prefers a warm, moist environment. It has some drought tolerance and has no requirement for air humidity. However, when soil moisture content is less than 9%, japanese privet appears to grow slowly or reduce the number of branches, leaves, flowers and fruits. It grows best in temperatures between 20 to 30 ℃, but is hardy enough to tolerate temperatures around -12 ℃.

Watering

The mature Japanese privet is somewhat drought tolerant and therefore requires less water. Ensure that the soil moisture is about 20% wet, not too dry or muddy. Water when the soil is dry, and once before winter.

It is important to avoid watering seedlings excessively, because too much water can easily lead to pests and diseases. Spray water daily on the seedlings in the early morning or late afternoon, as midday watering can damage the root system. Japanese privet has a certain tolerance to salt and alkali, so there is no special requirement on the pH of the water. Tap water, rain water, or distilled water will do.

Soil

Japanese privet grows well in slightly acidic to slightly alkaline soils, with a suitable pH range of 6-7.5. It is best planted in deep, fertile, humus-rich, well-drained sandy loam or clay. It is very adaptable to soil and has a certain tolerance to salt and alkali. It is not picky about soil as long as the soil is slightly moist and not dry or wet.

Mulching

Spread a 3-inch-thick layer of mulch between Japanese privet shrubs during their first year in the garden. Leave a gap of 2 inches between the mulch and the trunk of the shrub to allow moisture to escape the soil. Remove the mulch the following year.

Fertilizing

Japanese privet does not have high requirements for fertilization. You can apply organic fertilizer twice each spring and autumn to encourage lush foliage and bright leaves. In summer, when the temperature is higher than 30 ℃ you should stop fertilization to prevent the dormant plants from root rot due to poor absorption. You should also stop fertilization during winter dormancy. When transplanting in spring, you can apply an organic fertilizer as a base fertilizer to increase soil temperature and promote plant growth.

Planting Instructions

Japanese privet has deep roots, so if it is used as a hedge, plant seedlings 40 cm apart. If planted as small trees, the distance between two plants should be at least 3 m. Spread a layer of organic fertilizer at the bottom before planting; this will increase the soil temperature, make the soil fertile, and promote faster growth. Once planted, it needs to be continuously watered for three days. After that, wait until the soil dries out before watering. Remember to provide shade when the sun is particularly strong.

Pruning

Japanese privet branches grow very fast, and need to be pruned 2-3 times a year. As a shrub, it can be pruned into various shapes. In summer, cut off branches that hinder the normal growth of the main branch, including unnecessary, messy, diseased, weak, and downward- or inward-growing branches. Prune again in winter and cut the main branch slightly shorter. Excessive pruning can cause slow growth or even death, so prune judiciously.

Transplant

For successful transplanting of Japanese privet, choose the ideal season of late spring to mid-summer, when the weather is warm and plants are thriving. Prioritize a location with well-drained soil and partial to full sun. Remember to water regularly post-transplant to ensure healthy growth.

Overwintering

During snowfall and freezing temperatures, shake off the snow and ice to reduce the freezing of the leaves and prevent the branches from being broken by snow. The “snow quilt” formed by the snow under the tree is a good thermal insulation layer. The snow layer has a protective effect on the roots and therefore does not need to be swept away.

Pests and Diseases

  • Common Pests 

Watch for signs of pest damage such as damaged leaves or whitish lumps on the stems. Spray the affected area with pyrethrin or other insecticidal soaps. Prune off the damaged areas and discard the pruned matter into a green waste can rather than composting it.

  • Common Diseases

Monitor Japanese privet shrubs for diseases such as root rot and verticillium wilt. Look for foliage loss, discolored leaves or fungal growth on the trunk. Treat it by decreasing irrigation and pruning off the affected branches. Allow the soil to dry out to a 3-inch depth between waterings.

III. Uses and Benefits 

  • Ornamental uses

Japanese privet (Ligustrum japonicum) is an attractive waxy-leaved shrub primarily grown as a low-maintenance hedging plant. Because of its long, elegant trunk, japanese privet makes for a good stilted hedge to be used to add screening above fences and walls. This shrub makes for a rewarding addition to city, cottage, and informal gardens. It grows attractively with maiden grass, potentilla, or euonymus.

  • Medicinal uses

The fruit is used in herbal medicine as a cardiotonic, diuretic, laxative, and tonic treatment. Ligustrum japonicum has different effects on osteogenic and adipogenic cells within the body. By examining the ALP activity and lipid accumulation using human bone marrow derived from stromal cells, an increase of ALP production will be found. The accumulation of intracellular triglycerides are well-known markers of osteoclastogenesis and adipogenesis. The increase in ALP is due to the substances within the fruits of Ligustrum japonicum. Ligustrum japonicum fruits have been used in traditional medicinal practices and supplements in Korea and Japan. It has been reported to have various bioactivities. Which is why Ligustrum japonicum is used for tonic effects in traditional Japanese medicine.

Wax-leaf Privet (Ligustrum japonicum) Details

Common name Amur, Common Privet, Curlyleaf Ligustrum, Japanese Privet, Privet, Wax-leaf Privet
Botanical name Ligustrum japonicum
Plant type Perennial
Hardiness zone 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b
Growth rate Fast
Harvest time Fall
Height 6 ft. 0 in. - 12 ft. 0 in.
Width 6 ft. 0 in. - 12 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Clay
Flower color White
Leaf color Green