Prepared by Karen Russ, HGIC Horticulture Specialist, Clemson University. (New 03/07.)
Japanese pittosporum (Pittosporum tobira) is a tough, evergreen shrub, commonly grown in mid and coastal South Carolina. It is native to southern Japan and China. The attractive, dense evergreen foliage and mounded form, along with adaptability to many growing conditions, make it popular in landscapes as hedges and foundation plantings. Excellent salt tolerance makes pittosporum well suited for planting near the beach.
Japanese pittosporum hedge.
Karen Russ, ©HGIC, Clemson Extension
At maturity, the species can reach 8 to 12 feet or more in height, with a 12 to 18 foot spread. The natural form is dense and mounded. Pittosporum responds well to pruning and can be maintained for many years at smaller sizes. Heavy, frequent pruning may mean sacrificing the fragrant flowers. Several cultivars, such as 'MoJo' and 'Wheeler's Dwarf', have been selected for compact growth, some reaching as little as 2 to 3 feet tall at maturity.
Japanese pittosporum grows rapidly to 8 to 10 feet tall, and then growth slows considerably. Dwarf cultivars grow more slowly than the species.
Glossy evergreen leaves are tightly arranged in whorls at the ends of the branches. Variegated forms are perhaps even more common in the landscape than the dark green species due to the appeal of their gray-green and cream leaves.
Pittosporum bears extremely fragrant, orange-blossom scented, flower clusters in early to mid spring. The cream-white flower clusters are two to three inches wide and very showy against the dark green foliage of the species plant. They are less visible against the lighter leaves of variegated cultivars, but just as highly scented.
Variegated Japanese pittosporum foliage.
Karen Russ, ©HGIC, Clemson Extension
Pittosporums are well suited for hedges and screens due to their rapid growth rate, density and toughness. They also make very attractive small, multi-stemmed trees when lower branches are removed. Dwarf cultivars are attractive in foundation plantings, as high ground covers or mass plantings, and in containers.
Pittosporums are very tolerant of a range of soil conditions, so long as the soil is well drained. They are very drought tolerant once established, although they are most attractive and healthy when provided with regular and adequate amounts of water, especially while becoming established. They are not at all tolerant of poor drainage or excessive moisture, which can lead to rapid death from root rot diseases.
Japanese pittosporum will grow well in both full sun and shade, and is very heat tolerant. Hardy through zone 8, pittosporums can suffer from cold damage if they are grown in the upper Piedmont. Although they are sometimes seen growing in sheltered locations in the upstate, there is the risk of losing plants in hard winters. Bark splitting from cold damage can increase susceptibility to fungal galls.
If flowers are desired, pittosporums should only be pruned immediately after flowering. Pruning too late in the season may remove next year's flowers.
Pittosporum has good salt tolerance, including tolerance to salt spray.
Propagation is by semi-hardwood cuttings taken from mid July to September and treated with a root-promoting compound. Cuttings root best in a well-drained potting medium such as 50% peat and 50% perlite. Maintain high humidity around the cuttings. Generally, pittosporums are very easy to propagate.
Insect problems include cottony cushion scale, mealy bugs and aphids. Horticultural oil sprays are effective against both. Sooty mold is a certain sign of aphid or scale infestation.
Root rot diseases can be lethal for pittosporum, particularly in poorly drained soil. Avoid planting in areas where water accumulates after rains.
Several leaf spot diseases can be problems. In general, ensure good air circulation, avoid overhead watering, and clean up fallen leaves to minimize these problems.
Please note: Chlorothalonil fungicides can cause leaf drop and even death, especially on variegated cultivars. Chlorothalonil (Daconil) is not labeled for use on pittosporum. Always read pesticide labels before use, and use only according to the directions on the label.
Several fungi can cause galls and dieback. Infection usually enters through wounds such as those caused by split bark from cold damage. Prune out diseased branches six inches below symptoms. Disinfect pruners between each cut with 70 percent isopropyl alcohol or a 10 percent bleach solution.
Magnesium deficiency can occur when the soil pH is too high. Yellowing at the edges and between the veins of mature or older leaves is a symptom of magnesium deficiency.
Numerous pittosporum cultivars and species are grown on the west coast. Most have not yet been tested in the Southeast, and the list of pittosporums that can be grown here is likely to increase.
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This information is supplied with the understanding that no discrimination is intended and no endorsement by the Clemson University Cooperative Extension Service is implied. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.