How to Grow Camellias? A Detailed Guide to the Latest Cultivation Methods

The cultivation history of camellias in China can be traced back to the Shu Han period, when people already placed great importance on the status of the camellia. The camellia was ranked among the “seven grades and three fates.” Because of its graceful plant form, dark green and glossy leaves, and brilliantly colorful blooms, it was highly sought after by people. Now let us take a look at how to grow camellias!

Growth Habits of Camellias

Camellias fear wind and love sunlight, and prefer high, open terrain, good air circulation, warmth and humidity, good drainage, and loose, fertile sandy loam, yellow earth, or humus soil, with pH 5.5-6.5 being optimal. The suitable temperature range is between 20-32°C. Growth stops above 29°C, and at 35°C the leaves will show scorching. A certain temperature difference is required, and environmental humidity should be above 70%. Most varieties can tolerate low temperatures of -8°C (natural overwintering; Yunnan camellias are slightly less cold-tolerant). In areas south of the Huai River, they can generally overwinter naturally. They prefer acidic soil and require relatively good air permeability. They can usually be cultivated in peat, rotted sawdust, red soil, humus, or a mixed substrate of the above. In spring, autumn, and winter, no shading is needed; in summer, 50% shading can be used.

Cultivation Methods for Camellias

1. Placement: Camellias prefer partial shade and fear blazing sun, so they are best placed in a warm, humid, ventilated, and well-lit location. When growing camellias, there should be ample sunlight in spring; in summer, attention should be paid to shading and avoiding direct sunlight. If camellias are placed on a balcony, they can often be scorched to death if one is not careful. During storage and transport, camellias must be protected from high temperatures and dry air; otherwise, buds and flowers are prone to dropping, affecting quality.

2. Temperature: Camellias naturally prefer a warm climate. The optimal growing temperature is between 18-25°C. The temperature at which flowering begins is 2°C. They are slightly cold-tolerant; common varieties can withstand low temperatures of -10°C, and they can also tolerate summer heat, but above 36°C their growth will be inhibited. Cultivating camellias requires a certain temperature difference, and environmental humidity above 60% is optimal. In areas south of the Huai River, they can generally overwinter naturally, while the Yunnan camellia variety among camellias is slightly less cold-tolerant.

3. Watering: Potted camellia cultivation should keep the soil moist but not waterlogged, so as to avoid alternating dry and wet conditions that affect growth. Generally, in spring, watering can be appropriately increased to promote sprouting and shoot growth; in summer, water in the morning and evening, and it is best to spray water on the leaves so that they become thoroughly wet. Do not water with hot water, and watering should avoid the high temperatures around noon; in autumn, watering should be moderate; in winter, watering should preferably be done around noon, and spraying once every two or three days is sufficient.

4. Fertilizing: Camellias like fertilizer. When potting, be sure to place a layer of base fertilizer in the potting soil, mainly phosphorus and potassium fertilizer. The best fertilizer is a mixture of decomposed bone meal, hair, chicken feathers, rice husk ash, poultry manure, and superphosphate. Normally, too much fertilizer should not be applied. Generally, after flowering, from April to May, apply 2-3 times a dilute fertilizer solution, and in November of autumn apply one slightly stronger liquid fertilizer. When fertilizing camellias, note that the proportion of phosphorus fertilizer should be somewhat larger to promote abundant flowers and vivid color.

5. Pruning: Camellias grow relatively slowly and should not be pruned excessively. Generally, it is enough to cut off leggy branches as well as diseased, insect-damaged, and weak branches. If there are too many flower buds on each branch, thinning can be done, keeping only 1-2 and maintaining a certain distance, while the rest should be removed early to avoid consuming too many nutrients. In addition, faded flowers should be removed promptly, which can also reduce nutrient consumption, helping the camellia grow robustly and form new flower buds.

6. Repotting: Potted camellias are best repotted once every 1-2 years. The new pot must be one size larger than the old pot, which helps the camellia roots spread and develop. The best time to repot camellias is in April of spring, though it can also be done in autumn. When repotting, combine it with changing the soil by appropriately removing part of the compacted old soil, replacing it with fertile, loose, breathable new potting soil, and first placing a layer of base fertilizer.

Flowering Period Management of Camellias

Generally, after “Start of Winter,” camellias will begin to bloom one after another. To make camellia flowers large and brightly colored and to improve their ornamental value, the following technical points must be well managed during the flowering period.

1. Fertilizer and water management: After “Start of Winter,” the flower buds of most camellia varieties have already become very swollen. At this time, decomposed organic fertilizer mainly composed of phosphorus fertilizer must be applied, watered on once every 7 days until the flowers open. A single camellia plant often has several buds, and most varieties cannot bloom at the same time. After the first flowers to open have faded, fertilizer still needs to be supplemented so that the later flowers bloom well and fully. However, after the flowers have opened, fertilizer can no longer be applied; otherwise, the plant will suffer fertilizer damage and die. During the flowering period, camellias have a relatively high water requirement. Whenever the potting soil is dry, water thoroughly at noon. The plant must not be allowed to lack water, which would cause the flowers to fade early.

2. Move them as little as possible: Camellias are very delicate during the flowering period and should be moved as little as possible, especially when moving them from indoors to outdoors. If they must be moved from indoors to outdoors, then move camellias that have already opened or are currently opening, and cover them with a nylon bag tied shut to prevent cold wind from causing cold damage. Unopened buds have stronger cold resistance and do not need bagging.

3. Pay attention to ventilation: Camellias should not be kept for long periods in an unventilated room. Windows should be opened every day for air exchange to facilitate normal opening of the buds.

4. Apply additional light fertilizer: For larger potted camellia varieties, such as Xiaotaohong and Jinjiang Peony, if many flowers open at the same time, the flowering period should be controlled to no more than 10 days, and light fertilizer should be applied promptly after flowering, with careful maintenance, so as to help them recover their “vitality.”

Pest and Disease Control of Camellias

1. Anthracnose

[Disease characteristics] Anthracnose is one of the common diseases of camellias. It generally occurs from June to July on the leaves of that year's seedlings. The lesions mostly begin from the leaf tip or leaf margin. At the initial stage, water-soaked greenish-brown lesions appear on the edges of the basal leaves, then expand into irregular large patches arranged in streaks with a layer of small black spots spreading over the entire leaf, and finally cause the leaves to drop.

[Control methods] ① Strengthen cultivation management, pay attention to applying organic fertilizer and phosphorus-potassium fertilizer to improve the plant's disease resistance, and promptly remove diseased leaves and burn them. ② After the spring shoots emerge, spray with 1% Bordeaux mixture to prevent infection by pathogens. ③ In the early stage of disease onset, spray with 65% zineb wettable powder plus 600 times water solution; or spray with 70% thiophanate-methyl wettable powder 1000-1500 times solution.

2. Sooty mold

[Disease characteristics] Sooty mold can damage both branches and leaves, and is more obvious on leaves. In the early stage of disease, small sooty mold spots appear on the diseased parts, then gradually expand and connect into patches, covering most of the plant with a sooty mold layer. After the pathogen parasitizes, it not only absorbs nutrients from the flowers but also seriously affects the plant's photosynthesis and respiration, causing massive leaf drop.

[Control methods] ① Do not plant too densely; keep ventilation and light transmission between plants good. ② Do not allow humidity to become too high; control conditions that breed the pathogen. ③ During the disease period, spray with 0.3 degree Baume lime-sulfur mixture, once every 10-15 days, for a total of 3 sprays. ④ You can also spray with 50% thiophanate wettable powder 500 times solution, once every 7-10 days, 3 sprays, which can achieve a therapeutic effect.

3. Root-knot nematode disease

[Disease characteristics] Root-knot nematode disease harms the roots of camellias, turning the roots dark brown and causing root nodules to rot and rupture. The main root swells, new fibrous roots do not grow, the aboveground plant stops growing, and the entire plant gradually dies.

[Control methods] ① Before potting, disinfect the potting soil to kill the disease-causing organisms. ② After discovering the disease, immediately use sterilized potting soil as the potting medium and repot. ③ Before repotting, the potting soil can be exposed to the blazing sun for 2-3 days before use. ④ A solution made from 1,2-dibromo-3-chloropropane plus 100-150 times water can be used to spray the soil for disinfection, but soil treated with this chemical must be piled for 20 days before being used for potting. Otherwise, it will damage the root system.

4. Cloud-pattern leaf blight

[Disease characteristics] Cloud-pattern leaf blight harms young branches, leaves, and flower buds. Leaf lesions mostly occur at the leaf tip and leaf margin. In the early stage, the lesions are semicircular or irregular, yellow-green, then gradually turn brown, and in the later stage the lesions become gray-white with dark brown edges. In the later stage, diseased leaves are brittle and fall off very easily; lesions on shoots are strip-shaped, dark brown, and slightly sunken, and in severe cases the branches die. The disease period is from May to August.

[Control methods] In early summer in June, when the temperature rises suddenly and blight spots appear on the leaves, pesticide should be sprayed for protection. In August, when rainfall is greater than 40 mm and the average relative humidity is greater than 80%, spray immediately. You can choose 75% chlorothalonil 800 times solution, 50% carbendazim 1000 times solution, or 50% benomyl or 70% thiophanate-methyl 1500 times solution for control. After spraying carbendazim, benomyl, or thiophanate-methyl, tea can only be picked after an interval of 10 days; the safety interval for chlorothalonil is 14 days. Non-picking tea plantations can also be sprayed with 0.7% half-strength lime Bordeaux mixture.