Osmanthus fragrans is an evergreen broadleaf shrub or small tree that is known by many common names, most of which allude to its powerful fragrance: fragrant tea olive, sweet osmanthus, sweet olive, fragrant olive. Long grown as a large indoor plant, fragrant tea olive is increasingly popular as an outdoor garden plant in warmer climates, USDA zones 8 to 11.
I. Appearance and Characteristics
Osmanthus fragrans (lit. ’fragrant osmanthus’), variously known as sweet osmanthus, sweet olive, tea olive, and fragrant olive, is a species native to Asia from the Himalayas through the provinces of Guizhou, Sichuan and Yunnan in Mainland China, Taiwan, southern Japan and Southeast Asia as far south as Cambodia and Thailand.
In China, it is the “city flower” of the cities of Hangzhou, Zhejiang; Suzhou, Jiangsu; and Guilin, Guangxi. In Japan, it is the “city tree” of Kitanagoya, Aichi Prefecture; Kashima, Saga Prefecture; Beppu, Ōita Prefecture; and the “town tree” of Yoshitomi, Fukuoka Prefecture.
It is an evergreen shrub or small tree growing to 3–12 m (9.8–39.4 ft) tall. The leaves are 7–15 cm (2.8–5.9 in) long and 2.6–5 cm (1.0–2.0 in) broad, with an entire or finely toothed margin. The flowers are white, pale yellow, yellow, or orange-yellow, small, about 1 cm (0.39 in) long, with a four-lobed corolla 5 mm (0.20 in) diameter, and have a strong fragrance; they are produced in small clusters in the late summer and autumn. The fruit is a purple-black drupe 10–15 mm (0.39 – 0.59 in) long containing a single hard-shelled seed; it is mature in the spring about six months after flowering.
II. How to Grow and Care
Sunlight
Plant fragrant tea olive in full sun. Offer partial afternoon shade in climates with very hot summers.
Temperature and Humidity
These plants are typically winter hardy to about 10 degrees Fahrenheit, provided temperature drops are gradual. But it can be damaged if temps fall too quickly from warm conditions to 20 degrees or so. It is rated as hardy in USDA zones 8 to 11. This plant does well in humid regions.
Watering
Fragrant tea olive has average watering needs. Watering established plants is necessary only when there is no weekly rainfall. Fragrant tea olive is somewhat drought-tolerant once established, but don’t expect it to thrive during extended droughts unless you water. Young plants should be regularly watered for the first year or so.
Juni from Kyoto, Japan
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Soil
Fragrant tea olive will grow easily in any good garden soil, but an average, moist, well-drained soil is best. These plants prefer an acidic to neutral soil (pH 5.0 to 7.5).
Fertilizing
Tea olives can benefit from a single spring feeding with a time-release shrub and tree fertilizer, ideally containing sulfur or iron. Never feed a tea olive immediately before cooler winter weather begins, as new growth stimulated by feeding can be damaged by frost. The exception is potted plants being moved inside for the winter—these do benefit from a light feeding as they move indoors.
Pruning
Osmanthus plants only need pruning if they get too big or develop unattractive or dead branches. But fragrant tea olive, like other species of the genus, can be trained as a small tree, shrub, or espalier, and it can be used in hedges. Clip its tips to encourage growth and maintain the desired size. Make cuts 1/4 to 1/2 inch above a lower branch junction.
Prune at the end of winter before buds appear. If you choose to prune, be careful not to overdo it, as too much pruning can prevent the plant from blooming. It can sometimes take as much as two years for the plant to resume good flowering after a hard, poorly-timed pruning.
Propagation
TANAKA Juuyoh (田中十洋)
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Tea olives are generally most often propagated by stem cuttings taken in the late spring or early summer. Here’s how to do it:
- Prepare a mixture of sand and potting mix in a 1-gallon nursery container.
- Use clean, sharp pruning shears to snip semi-hardwood cuttings that are about 8 inches long, then remove the bottom leaves.
- Dip the bottom of the cutting in rooting hormone, then plant it in the sandy rooting medium.
- Place in a bright outdoor location (but out of direct sunlight) and keep moist until roots develop. This can be a lengthy process, requiring as much as three or four months.
- When roots are well developed and new growth has started, the plant is ready to be transplanted. With luck, a cutting taken in spring may be ready to plant by late fall or early winter, but it’s not uncommon to grow it indoors or in a sheltered outdoor location until the following spring.
Potting and Repotting
Fragrant tea olives, as well as other species of Osmanthus, are often grown as potted plants in regions where they are not hardy. They can even be grown as houseplants, though they will require frequent tip-pruning to keep the plants at a manageable size. It’s quite common to grow a fragrant tea olive in a large pot filled with standard peat-based potting mix, moving it indoors for the winter, then back outdoors during the warm spring and summer months. A heavy clay or ceramic pot is recommended to prevent tipping; make sure the container has good drainage.
When grown indoors, a fragrant tea olive plant will need a very bright location with plenty of sun, and make sure to keep it away from heat ducts. These plants may struggle if grown indoors all year. It’s best to make sure they get a minimum of several weeks outdoors in a sunny location during the spring and summer.
Overwintering
No winter cold protection is necessary for these plants, provided you are growing them in the established hardiness range (zones 8 to 11). Fragrant tea olive is the most cold-hardy of the Osmanthus species, and even zone 7 gardeners may be able to grow them successfully in sheltered locations. Young shrubs may benefit from a cage of hardware cloth to protect them against gnawing creatures such as rabbits.
iv78x
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Potted shrubs should be moved indoors for the winter if you live in a region where nighttime temperatures will drop below 40 degrees Fahrenheit; you don’t want to risk frost damage. Potted tea olives being moved indoors will benefit from a top-dressing of time-release fertilizer to keep them growing. But with outdoor garden shrubs, withhold feeding for the winter.
Pests and Diseases
Common Pests and Diseases
The only serious pest problems with fragrant tea olive are scale and aphids, which can be especially troublesome with plants moved indoors for the winter. Treat by spraying with horticultural oil.
Botryosphaeria canker can affect these plants, especially those that are stressed by drought. Cercospora leaf spot and anthracnose may occasionally occur. Phytophthora and Pythium root rots are sometimes seen in poorly drained or excessively wet soil.
Common Problems
There are few common complaints with fragrant tea olive, but the plant can be sensitive to cold, and unexpected cold snaps can damage the flower buds for the following year, and even stunt the plant’s growth for a full year or two.
Another common problem is that fragrant tree olives can drop their leaves unexpectedly. This most often occurs with potted plants grown indoors, but it’s also possible with outdoor garden plants. Likely causes of leaf drop:
- Not enough water: These plants need moisture, and dry indoor winter air may cause desiccation that causes the leaves to drop. Indoor potted plants may well need daily light watering during dry winter months.
- Extreme temperature swings: This can happen during the transition period as potted plants are moved from outdoor to indoor locations, or indoors to outdoors. Treat potted tea olives as you would seedlings, “hardening them off” by gradually acclimating them to new conditions.
- Too little light: Again, this is more likely with potted plants moved indoors, where it can be hard to find a sunny winter location. Potted tea olives will need the brightest window you can find—or will need artificial light. Outdoor plants that drop leaves may be signaling that they are in a spot that’s too shady.
- Pest and disease problems: Unhealthy tea olives often drop their leaves, so make sure your plant is not struggling with scale or fungal disease.
III. Uses and Benefits
salchuiwt
CC BY-SA 2.0
- Culinary
In Chinese cuisine, its flowers may be infused with green or black tea leaves to create osmanthus tea (桂花茶; guìhuāchá). The flowers are also used to produce osmanthus-scented jam, osmanthus cakes, dumplings, soups, and osmanthus liquor. Osmanthus jam is used as an ingredient in a type of gruel called chátāng, which is made from sorghum or millet flour and sugar mixed with boiling water. This dish is associated with the northern city of Tianjin, although it may also be found in Beijing.
Osmanthus is also used for making many traditional Chinese desserts, such as osmanthus tangyuan with rice wine syrup (桂花酒釀湯圓).
- Repellent
In some regions of North India, especially in the state of Uttarakhand, the flowers of sweet osmanthus are used to protect clothes from insects.
- Medicinal
In traditional Chinese medicine, osmanthus tea has been used as an herbal tea for the treatment of irregular menstruation. The extract of dried flowers showed neuroprotective, free-radical scavenging, antioxidative effects in in vitro assays.
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