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Zhi Zi

Botanical name: Gardenia jasminoides
Common name: Gardenia fruit, Cape jasmine fruit

Family: Rubiaceae, madder family
Part used in Chinese medicine:  fruit

Major Chinese medicine actions:
Resolves constrained heat, soothes irritability,
clears damp heat downwards, cools blood

Zhi Zi

Zhi Zi

Zhi Zi

Zhi Zi
Photo Credits: (top to bottom)
Photo 1: Gardenia jasminoides; 02/2007; author Bernard Loison; permission under GFDL
Photo 2: Gardenia jasminoides; 06/2006; author Kenpei; permission under GFDL
Photo 3: Gardenia jasminoides; 06/2006; author Kenpei; permission under GFDL

Comments:
A common garden plant, the gardenia is native to central and southern China, and grows along wild along streams in Hong Kong, flowering in early summer with a lovely fragrance. Hong Kong was originally a small fishing village where a profusion of gardenias prompted the name, translated as Hong "fragrant" and Kong "harbor". The plant is now cultivated around the world for its flowers, as both an indoor plant, and in warmer climates, an outdoor plant. In Guangzhou, China an orange dye obtained from the gardenia fruit is used to color soy bean curd (tofu) a yellow color.

Gardenia jasminoides is the main species used in Chinese medicine, but Gardenia rotundifolia is also an acceptable species. The herb was first mentioned in the Shen Nong Ben Cao Jing, the oldest Chinese herbal text, where it is designated in the second of three classes of herbs.

Growing and Propagation

The plant is a bushy evergreen shrub with glossy green leaves and single or double creamy white flowers that bloom throughout the summer. It grows up to 6 feet in height, but in cooler regions may only reach 2-3 feet high. As the flowers die, the five-pronged calyx eventually grows a small orange fruit. Gardenias grow best in warm weather in full sun and most varieties will not survive temperatures below 20 degrees F. A recent cutivar of Gardenia jasminoides, called "Frostfree", was developed to withstand cold to 5 degrees F.

Flowering can be encouraged by side dressing the plants with manure or blood meal, and by keeping the soil pH around 5 to 6, slightly acid to neutral. The plants do well if fertilized with a fish emulsion every 3-4 weeks during the bloom season

Propagation can be achieved by either seed or cuttings, though both can be difficult. Cuttings can be taken any time of year, but best in March or April. They should be cut from the soft, sappy current years growth as opposed to the hard woody branches. Taking a piece 3-8 inches long, the bottom of the cutting should be cut just below a node, or joint. After removing the lower leaves, it can be planted obliquely in rooting medium and watered well. It will generally root in 6-8 weeks if kept in a warm, humid environment. The rooting medium should be kept at 68-77 degrees F, heated from below, and misted frequently. Plants from cuttings should be protected for the first year until they can be planted in a permanent place in the garden the following spring, planted with the crowns relatively high.

Seed can be planted in the spring in pots in a greenhouse where temperatures are maintained at 70-75 degrees F. They should be sown about 1 1/4 inch deep in a lime free sowing mix. Germination takes 3-8 weeks. When seedlings are about a foot high, they can be transplanted to a permanent location in the garden.

Harvesting and Preparation

Gardenia fruits are harvested when they begin to turn yellow, usually after a frost in October. It can be difficult to dry the fruits without loosing their natural color so they are first briefly scalded in boiling water (with or without 8% alum added for every kilogram of herb) or steamed for 30 minutes. The fruit is then dried in the sun for several days, and then dried completely in shade with good air circulation. The best quality Zhi Zi for medicinal use consists of small, unbroken fruits with a thin pericarp, having a reddish yellow in color inside and out.

 

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