Japanese Cheesewood (Pittosporum tobira)

Japanese cheesewood, Australian Laurel, Japanese Pittosporum, Mockorange, Mock Orange, Pittosporum

The name of the Japanese pittosporum can be deceiving. It is not a true orange plant, it instead gets its name from the fact that the highly fragrant flowers have a distinct citrus scent. The flowers don’t last for a long time, only about two weeks, but the dark evergreen foliage is attractive all year long and the plant makes a great addition to a border or as a stand-alone plant.

I. Appearance and Characteristics 

Pittosporum tobira is a species of sweet-smelling flowering plant in the Pittosporum family Pittosporaceae known by several common names, including Australian laurel, Japanese pittosporum, mock orange and Japanese cheesewood. 

It is native to parts of Eastern Asia but has been introduced as an ornamental plant in many parts of the world. In China, it is found in the Fujian province and has been introduced in several others. In Japan, it is found in Honshu and the islands of Kyushu, Shikoku, as well as the Ryukyu Islands. It is also found in South Korea and northern Taiwan. It has been introduced to parts of the United States, and may be found in California, North Carolina, Georgia, and Florida.

It grows in forests, limestone areas, slopes, sandy seashores, and roadsides, usually to 1,800 meters (5,900 ft) above sea level.

It is an evergreen shrub which can reach 10 m (33 ft) tall by 3 m (10 ft) broad, and can become treelike. It can also be trimmed into a hedge. The leaves are oval in shape with edges that curl under and measure up to 10 cm (4 in) in length. They are leathery, hairless, and darker and shinier on the upper surfaces. The inflorescence is a cluster of fragrant flowers occurring at the ends of branches. The flower has five white petals each about a centimeter long. The fruit is a hairy, woody capsule about 1 cm wide divided into three valves. Inside are black seeds in a bed of resinous pulp.

Although not typically considered edible, the nutritional composition of P. tobira seeds have been analyzed. The seeds are mostly carbohydrates (71.3%) while their low fat content (5.6%) means it cannot be classified as an oily seed. The high ash content may suggest the presence of considerable amounts of inorganic nutrients in this plant.

This shrub is a common, drought-tolerant and fairly hardy landscaping plant. Many cultivars have been developed, including dwarf forms (such as Wheeler’s dwarf) and the popular ‘Variegata’, which has variegated leaves.

II. How to Grow and Care

Sunlight

While the japanese pittosporum grows well in both the sun and partial shade, varieties that have variegated or purple leaves will only keep their unique color when grown in full sun. Other varieties will make do with between 2-6 hours of sun each day, with more sun usually equating to stronger and healthier growth.

Temperature

Native to southern Australia, the Japanese pittosporum is a warm-climate plant. Hardy down to -8 ℃, the plant will sometimes even have colder temperatures, but not without significant damage. However, constantly freezing temperatures combined with a cold wind will soon be deadly for the plant. Heat and humidity aren’t a problem for the japanese pittosporum – it will happily handle the hottest part of your garden. Once established, the plant is extremely drought-tolerant too.

Watering

Although drought-tolerant, the japanese pittosporum does best when given consistent moisture, so you will need to water regularly in the spring and summer. However, the plant doesn’t take well to being over-watered, so make sure that the topsoil has sufficiently dried out in between waterings. If your japanese pittosporum has been newly-planted, water 3-4 times a week for the first couple of months. Then, drop this down to around once a week. Cut back on watering in the winter.

Soil

While the japanese pittosporum adapts to a variety of soil types, it does best in a well-drained and loamy soil, with a neutral to slightly acidic soil pH of 5-7. If your soil is extremely heavy or not free draining, dig in an organic material around 1 m deep – this will improve drainage while also enriching the soil. You can also mix in equal amounts of compost and a slow-release fertilizer.

If you are growing your Japanese pittosporum in a pot, a high quality light potting mix is best.

Fertilizing

Although not necessary, the japanese pittosporum benefits from a balanced, slow-release fertilizer each spring, such as an 8-8-8. Unless your soil is deficient in certain nutrients, use the lowest recommended concentration rate – over-fertilizing your plant will make it more vulnerable to pests and diseases. Apply when the soil is moist for maximum absorption.

Planting Instructions

Although the Japanese pittosporum grows well from seed, germination can take a long time, so you would be best off planting seedlings or small plants. Planting should always be done in the spring or the fall.

Choose a location in your garden that receives sunlight for some or all of the day, but is sheltered from cold winds. If your soil is heavy, dig a hole twice the size of the root ball and amend with compost, as this will encourage a stronger root system to develop. Then, remove some soil from the root ball and plant at the same depth that it was previously at, filling the hole back in and firming down the soil. Water thoroughly after planting.

Pruning

The japanese pittosporum takes well to pruning, allowing you to trim it into a variety of shapes, sizes, and styles. Always prune in the spring and never in the fall or winter – if the cold gets into the cut ends, the whole plant could die. The pruning method chosen should depend on whether you want the plant to grow as a tree, a hedge, or a shrub.

Tree pruning: When your plant is small, make sure that all stems are 10 to 15 cm apart, removing any extras. Once your tree is 1.5 m tall, cut basal suckers back to 6 mm of the trunk to shape the tree. Remove lower branches, leaving lateral branches on the top 61 cm of growth. Continue to do this each year until your tree has grown to your desired size.

Hedge pruning: In the first 2 years after planting your japanese pittosporum hedge, cut away half of any new growth each spring. In the third year, start shaping the hedge – keep the base wider than the top, so that the sides are slightly sloping, as this will allow the sun to reach all parts of the plant. Once your hedge is high and wide enough, trim closely each spring.

Shrub pruning: Each spring, remove any weak, wayward, dead, or diseased branches. You will also need to cut back the main branches to maintain the size of the plant – any cuts made should be 6 mm from an outward-facing branch.

Propagation

The best way to propagate the Japanese pittosporum is by taking semi-hardwood cuttings in the summer. Look for a firm, 10 to 15 cm lateral shoot that’s semi-mature, with fully-formed leaves from this season’s growth. Cut at the base and keep moist and away from direct sunlight until planting time.

To plant your japanese pittosporum cutting, remove any foliage from the bottom half, and then dip the cut end into a rooting compound. Bury the bottom half of the cutting into your planting medium, mist with water, and then cover with a clear plastic bag. Mist daily until it has rooted, which usually takes about 3-4 weeks. After that, it is ready to be transplanted.

Transplanting

The best time to transplant Japanese pittosporum is during the fresh beginnings of early to mid-spring. Choose a sunny or partially shaded location to ensure its optimal growth. Remember to provide well-draining soil for a thriving Japanese pittosporum. Happy transplanting.

Pests and Diseases

Mock Orange plants are susceptible to damage from common pests like aphids, mites, and leafhoppers.

These pests are easy to deal with and are treated with simple pesticides like white oil.

Other than these, Mock Orange can get cotton cushiony scale, pit-making pittosporum scale, and root-knot nematodes.

Consult your local botanical garden or nursery to find out if these are causing damage to your plant and then ask for advice for treatment.

When it comes to diseases, Mock Orange is vulnerable to a fungal pathogen called Erythricium salmoni color.

This particular fungal infection appears as galls. It can cause dieback disease called pink limb blight.

III. Uses and Benefits 

Mock Orange plants are very versatile when it comes to their use.

They are very popular in landscaping and are planted in both beds and borders in all sizes of gardens.

In China, Japan, and China, the plants are placed in pots and used for ornamental purposes outside of buildings.

The sweet citrusy scent of the Mock Orange flower is also popular in floriculture.

The plants are cultivated in large quantities to be used for decorative purposes and as cut flowers.

Similar to Boxwood, the Mock Orange plant is used as a wind-resistant hedge in areas where there is maritime exposure.

They are often used in shelterbelt plantings.

Japanese Cheesewood (Pittosporum tobira) Details

Common name Japanese cheesewood, Australian Laurel, Japanese Pittosporum, Mockorange, Mock Orange, Pittosporum
Botanical name Pittosporum tobira
Plant type Perennial
Hardiness zone 8a, 8b, 9a, 9b, 10a, 10b
Growth rate Fast
Harvest time Fall
Height 8 ft. 0 in. - 13 ft. 0 in.
Width 8 ft. 0 in. - 13 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Clay
Flower color Cream/Tan
Leaf color Green