The latest oleander cultivation methods, explained in one article

Oleander is an evergreen upright large shrub of the genus Nerium in the dogbane family Apocynaceae, with large, showy flowers and a long flowering period, often cultivated as an ornamental plant. It is grown in all provinces and regions of China, especially in the south, and is often planted in parks, scenic areas, roadsides, or around rivers and lakes. North of the Yangtze River, cultivated plants must overwinter in a greenhouse. Let us take a look at the cultivation methods of oleander!

Growth habits of oleander

Oleander likes a warm and humid climate and is not very cold-hardy. In the regions south of the Yangtze River basin in China, it can be planted in the open ground, but in Nanjing the branches and leaves are sometimes frozen and withered, and young seedlings may even freeze to death. In the north it can only be grown in pots for ornamental purposes, overwintering indoors. The white-flowered variety is slightly more cold-hardy than the red-flowered variety. Oleander is not tolerant of waterlogging, so a high, dry, and well-drained location should be chosen for planting. It likes light and fertilizer, and can also adapt to a relatively shady environment, but when planted in shade it produces fewer and paler flowers. It has strong sprouting ability, and the tree body recovers easily after damage.

Cultivation value of oleander

1. Ornamental: Oleander is a well-known ornamental flower. Its leaves are like willow and bamboo, and its red flowers blaze like peach blossoms. The corolla ranges from pink to deep red or white, with a special fragrance. The flowers are concentrated at the tips of the branches, gathered together like an open umbrella, funnel-shaped, with overlapping petals, in three colors: red, yellow, and white.

2. Environmental protection: Oleander has the ability to resist smoke, dust, and toxic substances, purify the air, and protect the environment. Its leaves are toxic to humans and have a strong resistance to harmful gases such as sulfur dioxide, carbon dioxide, hydrogen fluoride, and chlorine. Even if the whole plant is covered with dust, it can still grow vigorously, and people call it the “guardian of environmental protection”.

3. Medicinal use: The root bark of oleander has the effects of strengthening the heart and killing insects. The leaves have the effects of strengthening the heart, promoting diuresis, eliminating phlegm, and killing insects. The whole plant has the effects of strengthening the heart, promoting diuresis, inducing sweating, eliminating phlegm, dissipating blood stasis, relieving pain, detoxifying, and promoting rash eruption. It is used for asthma, epilepsy, heart failure, killing flies, and eliminating mosquito larvae.

Propagation methods of oleander

1. Sowing: After the fruit of oleander ripens, it can be sown immediately upon collection. After sowing, it is kept in a greenhouse and can only emerge after 3 months. When sown in the open ground in autumn, seedlings can emerge successively by Qingming the following year.

2. Layering: Oleander layering propagation is carried out during the rainy season. Branches near the ground surface are cut and pressed into the soil, and after about 2 months they take root and can be separated from the parent plant.

3. Water cuttings: Oleander water cuttings can be done during the growing season. Cut 30-40 cm long branches, split the lower end 4-6 cm with a small knife, and insert them into a glass container filled with water. In spring and autumn, when the temperature is suitable, roots can grow in 2-3 weeks. In summer, the water must be changed frequently to prevent deterioration of the water from causing root rot.

4. Stem cuttings: Oleander cuttings must meet the conditions of good quality, robust growth, and freedom from pests and diseases, and should be cut, shortened, and inserted immediately upon collection. To improve the survival rate of cuttings, during cutting, dozens of cuttings are neatly tied into bundles and soaked in 100 ppm ABT rooting powder No. 1 for 2 to 8 hours, or soaked in 30 to 100 ppm rooting powder No. 6 for 1 to 8 hours.

Cultivation methods of oleander

1. Watering: Although oleander likes water, it fears waterlogging. During continuous rainy days, accumulated water in the pot should be poured out promptly to prevent root rot. If watered too much, the leaves turn yellow and fall off one after another, affecting flowering the following year. In spring and autumn, watering should follow the principle of watering when dry and stopping when wet, so as to keep the pot soil moist. Summer is exactly the period of vigorous growth and flowering for oleander, so it needs more water. It is advisable to water once each morning and evening, and pay attention to frequently spraying and washing the branches and leaves to keep the leaf surface fresh and green. Move it indoors in mid-October. After moving indoors, watering should be controlled, and excessive water must be avoided, otherwise it is prone to root rot and leaf loss, affecting growth the following year.

2. Light: Oleander likes sunlight, so during the growing period it needs to be kept in a sunny place for care, otherwise it will produce fewer and paler flowers.

3. Temperature: Oleander should be planted in a wind-sheltered, sunny location. In winter, move it indoors to prevent freezing. A room temperature not lower than 0°C is sufficient. If the temperature is too high, it consumes nutrients and is unfavorable for growth and flowering the next year. Where outdoor temperatures are high in winter, soil can be banked up around it to protect against the cold.

4. Fertilizing: Oleander likes fertilizer. From the time it is moved outdoors until the flowers fade (First Frost), a thin liquid fertilizer can be applied about once every 20 days. After the Beginning of Autumn, oleander grows rapidly. At this time, fertilizer water can be applied about once every 15 days until just before it is moved indoors.

5. Pruning: Oleander is generally pruned four times: first after Grain Rain in spring, second during July and August, third during October, and fourth in winter pruning. If flowering indoors is desired, move it to a sunny spot indoors at about 15°C. Prune immediately after flowering, otherwise there will be fewer and smaller flowers, or even no flowers at all. Through pruning, the branches are evenly distributed, the flowers are large and colorful, and the tree shape is beautiful.

6. Diseases: Brown spot is an important disease on oleander. In the early stage of the disease, spray 50% benomyl wettable powder at 1000 times dilution, or 25% carbendazim wettable powder at 600 times dilution, or 36% thiophanate-methyl suspension concentrate at 500 times dilution. For the control of black spot, management should be strengthened to increase tree vigor, and when necessary spray 75% chlorothalonil at 700 times dilution.

Note: The whole plant of oleander is highly toxic, and accidental ingestion by humans or livestock is dangerous, so it should be avoided to plant it near wells and drinking water ponds. The floral fragrance of oleander can make people drowsy and reduce intelligence. The milky white liquid secreted by the stems, leaves, bark, flowers, and fruits all contains a highly toxic substance called oleandrin. Excessive contact can easily induce cancers of the respiratory and digestive systems, but a small amount of short-term contact will not cause too much of a problem.