Camellia japonica ‘Unryu,’ a member of the tea plant family, is an evergreen shrub or small tree. This species is cultivated from the Chi Dan buds and belongs to the Huadong camellia group, which has the most varieties among existing camellias.
Its leaves are dark green, occasionally with yellow patches. The flower is red, sprinkled with white lines and spots on its petals, resulting in a vibrant and charming display. As a highly valued camellia variety, it offers great ornamental value.
The Mandarin Duck Phoenix Crown variety is wind-resistant and sun-loving, and should be planted in a well-ventilated, warm and moist environment with good drainage and fertile sandy loam.
Camellia japonica ‘Unryu,’ a member of the tea plant family, is an evergreen shrub or small tree. This variety, developed from the Chi Dan buds, belongs to the Huadong camellia group.
This group boasts the most varieties among existing camellias. The leaves resemble those of the Chi Dan, but are wider, with a shorter point at the tip.
The leaf veins are more delicately detailed than the Chi Dan, often referred to as snake-skin-like. The dark green leaves occasionally exhibit yellow patches. The bright red flowers are marked with countless white radial lines or spots, creating a vibrant display.
Blooming for 3 months, it can be found in mountainous regions and plains. This particular variety of camellia is highly treasured for its ornamental value.
This particular camellia is a rare variety cultivated by humans.
The Mandarin Duck Phoenix Crown is a variety of camellia developed from the Chi Dan buds, belonging to the Huadong camellia group.
The leaves resemble those of the Chi Dan, but are wider, with a shorter point at the tip. The leaf veins are more delicately detailed than the Chi Dan, often referred to as snake-skin-like.
The flowers exhibit a range of colors, from all red to all pink, and half red-half pink, with red radial lines on pink and pink radial lines on red. Each tree boasts multiple flowers. The petals are arranged neatly like “hexagonal tiles,” with 8 to 10 rounds or more.
The leaf surface is bubbly, creating a snake-skin-like texture. Although it is easy to cultivate, the growth is slow, but the leaves and crown shape are attractive.
The vibrant red flowers are adorned with countless white radial lines or spots. The radial deep red streaks are numerous but not chaotic, giving the flower a stunning appearance.
The distinctive red and white colors are striking, making the flowers highly attractive. The rose double petal to full double petal type, medium-sized flowers, with 8-9 rounds of petals arranged in an orderly overlap, produce a moderate number of flowers.
The light green leaves are irregularly oval, with uneven surfaces. The plant is compact with moderate growth. The blooming period is in the middle to late season.
This species is wind-resistant, sun-loving, and should be planted in areas with good air circulation, warmth, humidity, drainage, and fertile sandy loam soil, loess or humus soil. The optimal pH range is 5.5-6.5.
It thrives best in temperatures between 20-32℃. Growth ceases above 29℃, and at 35℃, the leaves may scorch, hence a specific temperature difference is required. The environment humidity should be above 70%, and it can tolerate low temperatures of -8℃.
In regions south of the Huai River, it can generally naturally overwinter, prefers acidic soil, and requires good aeration for root development. Typically, peat, rotten wood, red soil, humus, or a mixture of these can be used for cultivation.
Camellias can be unshaded during the spring, autumn, and winter, and 50% shading can be used during the summer.
The soil acts as the basis for potted camellia growth, as camellia roots depend on the soil for growth and development. Water and nutrients needed for the life activities of camellias are mainly absorbed from the soil.
Camellias prefer slightly acidic, high humus, loose and airy mountain red (yellow) loam soil with a pH value between 5 and 6.5. Alkaline or heavy clay soils should not be used for potted camellia substrates.
Soil preparation: 50% mountain clay soil (matured red soil for crops), 40% sawdust or edible fungus residue, 10% cake fertilizer powder or livestock manure and phosphate fertilizer powder, mixed evenly, watered adequately, bagged and matured for more than 20 days in summer and autumn, and more than 30 days in spring and winter.
This soil is not only loose and airy, but also retains fertilizer and water, which is suitable for the growth and development of camellias.
Camellias need appropriate light but are afraid of direct sunlight in high temperatures.
In the spring and late autumn, camellias should be moved to a sunny balcony or ground to receive full-day sunlight, promoting plant growth and development, and encouraging flower bud differentiation and robust bud formation.
When entering the intense summer sunlight, the flower pots should be moved to a light-shaded, well-ventilated environment for maintenance, or they can be raised on the north balcony or under the south balcony.
They can also be covered with a 75% shading net from 9 am to 5 pm to avoid direct sunlight, which can cause leaf damage or small plant wilting. If conditions allow, camellias can be moved under a sun shed for a safe summer.
Temperature is one of the important conditions for camellia growth. Camellias prefer warmth, with the most suitable growth temperature being 18℃ to 25℃, and a relative humidity of 60% to 65%.
Camellia growth, spring shoots generally sprout in the middle and late March, start to bud in April, form the top bud in the middle and late May, stop growing, gradually differentiate into leaf buds or flower buds, and from flower bud formation to blooming takes 180 to 240 days.
Summer shoots sprout in late July and stop growing in early September. Although camellias are cold-resistant, if a cold wave invades and the temperature suddenly drops below 0℃ or encounters dry northwest wind, it will cause frost damage to the tender branches, and the flower buds will wilt due to frost damage.
Therefore, the flower pots should be moved to a south-facing position for maintenance to ensure safe overwintering.
Camellias have many leaves, which are large and have a fast transpiration rate. They prefer a humid climate and moist soil. Therefore, potted camellias need plenty of water. During the spring and fall growing seasons, water them once a day.
In summer, especially during the dog days, water them twice a day, in the morning and evening. If the ground is dry, water or spray the surface of the pot and its surroundings once or twice to maintain a certain level of air humidity, which will promote vigorous plant growth.
However, be aware that frequent watering and the use of tap water can cause the soil in the pot to become alkaline over time. To counteract this, add 0.5% to 1% ferrous sulfate or 5% to 8% vinegar to the water once a month, or spray it onto the leaves.
Camellias like moist soil, but be careful not to let water accumulate in the pot. If it rains and water accumulates, drain it promptly to prevent the roots from drowning or rotting.
Camellias are heavy feeders because they are robust plants with many leaves and a long flowering period. During the fertilizing process, apply enough liquid fertilizer and incorporate slow-release fertilizer when repotting.
Depending on the size of the pot, apply 3 to 80 grams of matured cake fertilizer powder or dried chicken or duck manure, mixing it evenly with the soil at the bottom of the pot.
According to the growth period of the plant, apply additional organic fertilizer. Except during the coldest and hottest months of winter and summer, apply matured cake fertilizer water once or twice a month.
To do this, dig a small trench about two inches deep around the edge of the pot, pour the liquid fertilizer into it, then cover it with soil to prevent odors.
Alternatively, you can mix the matured cake fertilizer powder with the soil around the edge of the pot and let the plant absorb it slowly. If you live in a city, you can buy special fertilizer for flowering plants at a flower market, which is both sanitary and safe.
To enhance the growth of camellias, during their vigorous growth period, apply foliar fertilizer once or twice a month, using 0.2% to 0.3% potassium dihydrogen phosphate and 1% to 2% plant growth regulator.
The principle of fertilizing is: it’s better to be light than heavy, dilute than concentrated, and less than more. You must adhere to the method of applying thin fertilizer frequently, especially avoid using fresh fertilizer.
Camellias like to grow in an environment where the air flows moderately and they love the breeze.
They appreciate the humidity brought by the southeast wind, but fear the northwest wind and strong wind, which can cause the water to evaporate too quickly and disrupt the balance of supply and demand, damaging the leaves and causing the plant to drop buds and flowers.
In winter, camellias should be placed in a sheltered and sunny environment with a certain temperature and humidity. In spring and autumn, move the pot to a balcony where it can get plenty of ventilation and light, and be moved by the breeze.
This not only promotes good plant growth, but also facilitates bud differentiation, bud growth and development, and reduces the occurrence of pests and diseases.
Years of practice have shown that moderate ventilation and appropriate sunlight can prevent pests and diseases.
During the rainy season, between May and June, select a young mother tree and cut a one-year-old tender branch from the top. This branch should be around 10 cm long. Remove the lower leaves and shave the area below the node flat with a blade.
Retain a terminal bud and a lateral bud at the top, along with 2-3 leaves. Insert the branch into a medium of river sand or gravel, at a depth of 1/3 to 2/3.
After insertion, cover with a grass curtain to provide shade and spray the leaves regularly to maintain humidity in the cutting bed and promote rooting. To improve the survival rate of the cuttings, they can be soaked in a solution of 50-100ppm ABT rooting powder for 8-12 hours.
Choose a robust seedling or a Camellia variety that is easy to survive from cuttings and use it as the rootstock. Cut it about 4-5 cm from the ground and split it about 1.5 cm deep in the center.
Use a 1-2 year old twig as the graft, retaining 1-2 leaves at the top. The lower part of the graft should be whittled into a wedge shape and inserted into the split in the rootstock. The cambium layers of both should closely align.
Then, bind them tightly with a plastic strip. After grafting, cover the graft with a plastic bag and tie it at the bottom, but not too tightly.
This will create droplets inside the bag, which will continuously drip onto the rootstock. Then, add a paper bag on the outside of the plastic bag to block direct sunlight.
Cut each bud node into a section, retaining one leaf, and about 1.5 cm long. Cut the bottom at an angle and then insert it into the medium. The depth should be enough to cover the twig. This method can fully utilize the branches and is suitable for mass propagation needs.
Cause and Symptoms: This disease is caused by the Camellia leaf anthracnose fungus (Colletotrichum gloeosporoides) infecting the leaves of the Camellia. This is the main disease of Camellia, with an incidence rate of 33%.
Symptoms often appear on the leaf edges, leaf tips, and both sides of the veins. Initially, dark green spots appear, which gradually expand into irregular large patches.
The color changes from brown to black. In severe cases, it can spread to the entire leaf, causing a large amount of leaf drop.
Disease Pattern: The occurrence of this disease is closely related to temperature and humidity. The general suitable temperature for disease occurrence is 25-28℃.
When the temperature is suitable and humidity increases, especially during continuous rainfall, it can promote the spread and development of the disease. The disease generally starts in April, peaks in June and July, and tends to stop after September.
Control Methods:
① Thoroughly remove diseased leaves.
② Prune diseased and dead branches in winter.
③ Before the disease period each year, spray with 1% Bordeaux mixture, once every half month.
④ Spray once a week with a 600-fold solution of Baume cleaner, continuously for 3-4 times.
⑤ Strengthen cultivation management and scientific weeding and fertilizing. Phosphorus and potassium fertilizers can be added in the spring, and a 0.15% solution of potassium dihydrogen phosphate can be sprayed before the leaves unfold.
Cause and Symptoms: This disease is caused by a parasitic alga, Cephaleuros virescens. Spots can appear on both surfaces of the leaves, but mainly on the upper surface.
In the early stage, the spots are as small as pinheads, gray-green in color, and gradually expand radially, forming nearly circular or irregular spots.
The spots are significantly raised, with a felt-like surface in fine stripes. In the later stage, the color of the spots changes from gray-green to dark brown. Due to the cover of the pathogen, it affects the photosynthesis of the leaves, thus weakening the growth of the camellia plant.
Disease Pattern: The parasitic alga overwinters in host tissues as filamentous nourishment. Under humid conditions, it produces motile spores that infect new plants.
This pathogen is a weak parasite. In hot conditions, camellia forests growing poorly due to poor ventilation and light are most severely affected by this disease.
Control Methods:
① Strengthen cultivation management, fertilize properly, trim timely, avoid over-shading in camellia forests, ensure ventilation and light penetration to improve the resistance of camellias.
② Use a 0.2%-0.5% copper sulfate solution for spray prevention.
Cause and Symptoms: This disease is caused by a pathogenic fungus, Glomerella cingulata, which infects both young and old branches of camellia.
The affected branches die, the leaves turn from green to pale yellow, gradually dry up and fall off from the top down, and eventually the entire branch dies.
Disease Pattern: The occurrence of this disease is related to the increase in spring temperature.
The pathogenic fungus overwintering on diseased trees gradually matures, disperses to nearby camellia branches with the wind, and invades the tea tree from new buds, tender branch wounds, leaf scars, grafting or pruning wounds, causing harm and reproducing in large numbers.
Control Methods:
① Remove and destroy diseased branches in winter.
② Remove unnecessary buds and weak branches to reduce the places where the pathogen can survive.
③ Isolate and care for diseased plants.
④ Before the buds of camellia plants sprout, spray fungicides such as methyl tobutin, fluazinam, and prochloraz, especially ensuring that the wounds on the branches are sprayed.
⑤ Apply more phosphorus and potassium fertilizers, and less nitrogen fertilizer.
Cause and Symptoms: This disease is caused by several pathogenic fungi, the most common of which are Phytophthora cinnamoni, Cylindrocladium crotalariae, and Armillaria, mainly infecting the root system of camellias.
The roots of the affected plants rot and turn black, the leaves turn yellow, the tips of the branches die, the flower buds fall off, and the plants gradually wilt and die.
Disease Pattern: The pathogen overwinters as mycelia in the soil or on diseased plants. In the spring of the following year, when the temperature and humidity are suitable, the mycelia germinate and spread in the soil, infecting the roots of the plants. The higher the temperature, the higher the incidence of the disease.
Control Methods:
① Diseased plants and nearby infected soil should be dug up promptly, and the soil around the plants disinfected with a 1% copper sulfate solution to prevent the spread of the fungus.
② Ensure good soil drainage to prevent waterlogging in the cultivation area.
③ Cultivate camellia varieties with strong disease resistance.
Causes and Symptoms: This disease is caused by the fungus Phyllosticta sp. The disease spots often occur on tender leaves, first appearing as light brown round stains.
Over time, the spots spread and change from light brown to dark brown, sometimes merging into larger patches or spreading across the entire leaf, causing a significant amount of leaf scorch and fall.
Disease Pattern: The fungus survives on the diseased remains of the host, with spores spread by wind and water. The disease generally begins in May, with the peak occurring from July to September, when there is a large fall of affected leaves.
Control Methods:
① In the early stages of the disease, a 70% solution of methyl tobujin at 1000-1500 times dilution, or a 25% solution of bactericide at 400 times dilution, can be sprayed for prevention and treatment.
② During dry periods, water can be sprayed on the leaves to inhibit the disease.
Causes and Symptoms: This disease is caused by the fungus Giborinia camelliae Kohn, which infects the petals of the Camellia. The affected flowers first show small brown spots, which gradually enlarge until the entire flower turns brown and withers.
Disease Pattern: The fungus can form mycelia on the flower stalk, and its spores can be spread by the wind. The incidence of disease is generally low in autumn. From December to the following March, as temperatures rise, the incidence of flower damage increases.
Control Methods:
① If Camellia flowers infected with this disease are found, they should be promptly removed and incinerated. Especially during blooming, fallen diseased flowers should be promptly cleaned up.
② Before blooming, fungicides like polyoxin can be sprayed on the buds 2-3 times.
③ Planting Autumn-blooming Camellia varieties or treating mid-late blooming varieties with gibberellin to make them bloom in Autumn can avoid the peak period of the disease.
④ Biological control methods can be used. Two types of fungi, Sporidesmium sclerotivorum and Coniotmyrium minitans, can be inoculated into the soil to kill the fungal spores.
⑤ Do not buy or cultivate Camellia plants that have flower blight.
Causes and Symptoms: This disease is caused by the harm of aphids and scale insects. The surface of the affected Camellia leaves is covered with a layer of fungal hyphae, forming a black “sooty” layer that hinders normal photosynthesis and gas exchange of the plant, severely restricting its growth and development.
Disease Pattern: The fungus prefers low-temperature, high-humidity environments, with 10-20℃ being the most suitable for its growth. Within this temperature range, the higher the temperature, the faster the fungus spreads.
Long-term overgrown weeds, high humidity, and poor lighting in Camellia forests are conducive to the occurrence and spread of the disease.
Control Methods:
The pests that cause sooty mold disease are mainly aphids and scale insects. Therefore, to prevent this disease, it is necessary to first control aphids and scale insects on Camellias. Once the pests are eliminated, the disease naturally disappears.
Flower Language: Humility, Caution, Virtue, True Feelings, Ideal Love, Elegance.
The vibrant camellia, capable of blooming in the early spring while the earth is still frozen, brings spring spirit and endless hope to life as it persists through the fragrant spring of peaches and plums.
Despite the ravages of time, the camellia remains full and enchanting, defying the cold frost with its beauty. In people’s minds, it is a symbol of beauty. The camellia has coexisted with humans, forming a fascinating culture around it over the course of more than 2,500 years.
Peggie was once a high school mathematics teacher, but she set aside her chalkboard and textbooks to follow her lifelong passion for flowers. After years of dedication and learning, she not only established a thriving flower shop but also founded this blog, “Flowers Library”. If you have any questions or wish to learn more about flowers, feel free to contact Peggie.
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