Gardenia Planting Methods and Key Cultivation Techniques
Gardenia is also known as Huangzhizi, Huangzhi, and Shanzhizi. The gardenia fruit is used as medicine; it mainly treats high fever from febrile diseases, restlessness and insomnia, toothache from excess fire, mouth and tongue sores, epistaxis, hematemesis, conjunctivitis, sores and swellings, icteric infectious hepatitis, favism, and hematuria; externally it treats bleeding from trauma and sprains and contusions. The root used as medicine mainly treats infectious hepatitis, bruises and injuries, and wind-fire toothache. The gardenia plant has luxuriant branches and leaves, beautiful flowers, and a rich fragrance, making it an excellent landscaping material for courtyards; it can also be used for pot culture or for making bonsai, and as cut flowers; the fruit peel is used as a yellow dye, and the wood is hard and fine-grained, making it a good material for carving. It is distributed in Zhejiang, Jiangxi, Fujian, Hubei, Hunan, Sichuan, Guizhou and other provinces. It is cultivated in most parts of the country.
(1) Plant Characteristics
Evergreen shrub or small tree, 100-200 cm tall. The trunk is gray, the branchlets are green, leaves are opposite or whorled on the main branches, obovate to oblong-elliptic, 5-14 cm long, glossy, entire; flowers are solitary at the branch tips or in leaf axils, white, strongly fragrant; the corolla is salverform, 6-lobed, fleshy. The fruit is ovoid with 6 longitudinal ridges; seeds are flat; the flowering period is June to August, and the fruit ripening period is October.
(2) Growth Characteristics
It prefers warmth, humidity, and good sunlight, but strong direct sunlight must also be avoided; it likes high air temperature and good ventilation, and requires loose, fertile, well-drained acidic soil, being a typical acid-soil plant. It is not cold-tolerant; in the Northeast, North China, and Northwest, it can only be grown as a potted flower in greenhouses. Gardenia is resistant to sulfur dioxide and can absorb sulfur to purify the atmosphere; 0.5 kg of leaves can absorb 0.002-0.005 kg of sulfur.
(3) Cultivation Techniques
1. Propagation Methods
It is mainly propagated by cuttings and layering; in addition, it can be propagated by sowing and division.
(1) Cutting Propagation
In the north, cuttings can be taken in greenhouses from October to November; in the south, cuttings can be taken at any time from April to the Beginning of Autumn, but the survival rate is highest between summer and autumn. Select healthy 2-year-old branches as cuttings, 10-12 cm long, remove the lower leaves, first dip them in vitamin B12 injection, then insert them into sand; under conditions of 80% relative humidity and a temperature of 20-24 degrees C, roots can form in about 15 days. If soaked in 20*10 to the -6th power to 50*10 to the -6th power indolebutyric acid for 24 hours, the effect is even better. When the rooted seedlings begin to grow, transplant them or pot them individually; they can bloom after 2 years.
(2) Layering Propagation
In April, select vigorous branches 25-30 cm long from 3-year-old mother plants for layering; if there is a three-forked branch, three seedlings can be obtained at one time from the fork. Generally, roots form after 20-30 days, and they can be separated from the mother plant in June, then divided and planted or potted individually the following spring.
(3) Seed Propagation
This is mostly carried out in spring; seeds germinate slowly, germinating about 1 year after sowing, and flowering after 3-4 years; potted plants in the north are not likely to produce seeds.
2. Field Management
Gardenia likes fertilizer, but it is best to apply frequent dilute fertilizer. It prefers slightly acidic soil with good drainage. After the seedlings are transplanted, topdressing can be done once a month; prune once each year from May to July, cutting off the shoot tips to encourage branching and form a complete crown. For mature trees, removing faded flowers helps vigorous flowering later and prolongs the flowering period. For potted gardenia, promptly pour off accumulated water after rain, and when leaves turn yellow, apply alum fertilizer water in time.
In the north, gardenia introduced from the south often has large flowers in the first year, smaller flowers in the second year, yellowing leaves that fall easily, and in severe cases the plant dies. The main reasons are that the soil in the north tends to be alkaline, the climate is dry, and the water quality is unsuitable for its growth. Therefore, when introducing it from the south, it should be transplanted with as much soil as possible. Usually water it with stored rainwater or water soaked with green grass and fruit peels; fermented salt-free swill can also be used for watering. If 0.1 kg of ferrous sulfate can be added to 50 kg of water, the effect is even better. During the vigorous growth period, use fertilizer water for topdressing, which can promote luxuriant branches and leaves and make the leaf color dark green and glossy. In spring and autumn, growth is slow. Apply a dilute liquid fertilizer once every 2-3 weeks. After summer begins, as the temperature rises, growth gradually becomes vigorous, and liquid fertilizer can be applied once every 7-10 days. In the morning and evening, clear water can also be used to sprinkle the leaf surfaces and nearby ground to increase air humidity. Before frost in autumn, move it into an environment with a winter temperature not lower than 0 degrees C to overwinter.
3. Pest and Disease Control
(1) Insect Pests
In environments with high humidity and poor ventilation, gardenia is susceptible to scale insect damage; it can be removed promptly with a small brush or sprayed with 100-150 times No. 20 gasoline emulsion, etc.
(2) Diseases
1) Sooty mold
It occurs on branches and leaves; after discovery, it can be wiped clean with clear water, or sprayed with 0.3 degrees Baume lime sulfur mixture or 1000-1200 times carbendazim.
2) Rot disease
It often occurs on the lower main trunk, causing the stem to swell and crack; after discovery, scrape it off immediately or apply 5-10 degrees lime sulfur mixture; only several applications will be effective.
(4) Harvesting and Processing
From September to November, pick the fruits, remove impurities such as fruit stalks, steam them briefly in a rice steamer or blanch them briefly in boiling water (alum may be added), then take them out and dry them in the sun. The fruits are not easy to dry, so they should be turned frequently to ensure good ventilation and prevent mildew and deterioration. The roots are dug in summer and autumn, washed clean, and dried in the sun.