Cultivation techniques of hydrangea

Hydrangea, also known as Hydrangea, is a deciduous shrub of the genus Saxifragaceae. The leaves are green, the flowers are bright, and the ornamental period is long, which is very popular among people.

Plant characteristics: The hydrangea is native to the Yangtze River Basin and the southern provinces. The natural plant height is 1 to 2 meters, and the pot height is controlled at 30 to 50 cm. Leaves opposite, obovate or elliptic, serrate at the edges. The inflorescence of the corymbum is terminal, 20 cm in diameter, nearly spherical, with less flowering and less flowers, and more asexual flowers. The color of the flower is changeable, initially white, gradually turning blue or pink, and the natural flowering period is from May to July.

Ecological habits: The hydrangea enjoys a warm and humid environment, with a suitable temperature of 18 ° C to 28 ° C and no less than 5 ° C in winter. The light should be half-shade, too strong blades will be burned and curled. Like loose and fertile soil, the water demand is large, but avoid water accumulation, and it is more resistant to harmful gases such as sulfur dioxide.

Common cultivar: V. hortensica: flowers are all sterile flowers, and sepals are ovate. V. coerulea Wils: Flowers are bisexual, dark blue, with blue or white edges. V.otaksa Bailey: flower infertility, large inflorescence, diameter up to 20 cm, thick leaf, spherical inflorescence, blue or light red, mostly used in gardens. V.maculata Wils: divided into two types: fertile and infertile, with narrow leaves and white edges for ornamental leaves.

Breeding method: Hydrangea can be propagated by means of ramets, beading, cuttings and the like.

Cutting in the greenhouse all year round. Generally, from May to June, combined with early spring pruning and post-flower shaping. Select semi-lignified pest-free branches, each 10 to 15 cm long, retain 2 to 3 knots and 1 to 2 leaves at the top, and insert them into the sand or vermiculite-based seedbed to cover the area properly. Keep the substrate moist, the air humidity is above 80%, and rooting begins around 18 days. Gradually reduce the number of water sprays and increase the light, and transplant them in about 1 month.

Cultivation management: Planting cuttings should be done in time after rooting. The hydrangea flowers are loose, fertile and well-drained. They are usually prepared in a ratio of 4:4:2 with humus soil, garden soil and organic fertilizer. The scale production should be carried out with grass carbon, perlite and organic fertilizer at 6:2: 2 ratio preparation, thoroughly disinfected before use.

Fertilization: The hydrangea is fertilized, and the organic fertilizer is usually chased once every half a month. There are more nitrogen fertilizers in the pre-growth stage. The flower bud differentiation and flower bud formation period are more phosphorus and potassium fertilizers. Foliar application of 0.1% to 0.2% potassium dihydrogen phosphate can also be carried out 2 to 3 times. After the flower buds pass through the color, the fertilization is stopped.

Watering: The transpiration of the leaves of the hydrangea is very large, so it must be watered in time. Even if the short-term water shortage is wilting, the leaves can be dried and the flowers are necrotic. Especially in the summer, it is necessary to reduce the transpiration by shading and keep the air humidity above 60%. In addition, the color of the hydrangea is affected by the pH of the soil, usually blue in an acidic environment and red in an alkaline environment. Therefore, the pH of the water is determined according to the desired color.

Temperature: Hydrangea is not resistant to high temperatures, and the temperature is required to be between 15 ° C and 25 ° C. The high temperature will make the plant's dwarf color fade and reduce the quality. After the flower buds are colored, the temperature is maintained at 10 ° C to 12 ° C to enhance the color and play a role in preservation.

Illumination: The hydrangea is shade-tolerant, and direct sunlight can cause sunburn, so it needs to be shaded. Generally, it is necessary to shading 60% during the growth period, and the shading should be properly shaded after the color is passed, so as to avoid the color becoming lighter and losing its brilliance.

Pruning: The germination of the hydrangea is strong, and many nutrient shoots will germinate at the base of the plant. In order to reduce nutrient loss, it should be wiped out in time. If the old branch needs to be replaced, a strong nutritional branch can be selected as a reserve branch. Shortly after flowering, keep 2 to 3 strong shoots to promote new shoots.

Flowering regulation: In order to open the Spring Festival of the Hydrangea, the healthy plants of 3 to 5 years old can be selected and treated at a low temperature of 2 °C to 4 °C for 14 days, then transferred to the greenhouse for heating, keeping 10 °C to 20 °C, 50 to 60 days. flowering. Pay attention to frequent ventilation, maintain good lighting conditions and high air humidity, apply organic liquid fertilizer every half month until flowering.

Pest control: There are few insect pests of the genus Hydrangea, mostly aphids, spider mites, etc., while ensuring good ventilation, spray the systemic drug to prevent it. Common diseases are mostly leaf diseases, such as white rot, gray mold, leaf spot, etc. Therefore, it is necessary to spray the drug regularly to prevent the disease, and it is necessary to spray the drug in time, and the diseased leaves can be removed and burned.