How to grow potted hydrangeas: the latest guide

Hydrangea is a common potted ornamental flowering shrub, also known as eight immortals flower, pink ball flower, grass hydrangea, etc. It is a shrub plant of the genus Hydrangea in the family Saxifragaceae, with very high ornamental value, full flower heads, large and beautiful, and its flower color can be red or blue, pleasing to the eye and refreshing to the spirit. Modern parks and scenic areas all plant it in masses to form landscapes. Now let us take a look at how to grow potted hydrangeas!

Growth habits of hydrangea

Hydrangea likes a warm, humid and semi-shaded environment. The optimum growth temperature is 18-28°C, and the winter temperature should not be lower than 5°C. Flower bud differentiation requires 6-8 weeks at 5-7°C. A temperature of 20°C can promote flowering, and maintaining 16°C after flowering can extend the viewing period. However, high temperatures make the flowers fade quickly. The potting soil should be kept moist, but watering should not be excessive. Especially in the rainy season, pay attention to drainage to prevent root rot caused by waterlogging. In winter, indoor potted hydrangeas are better kept slightly dry; if too humid, the leaves are prone to rot. It is a short-day plant. With more than 10 hours of darkness treatment per day, flower buds form in about 45-50 days. In normal cultivation, avoid direct sunlight, and 60-70% shade is ideal. The soil should preferably be loose, fertile and well-drained sandy loam, but changes in soil pH cause great changes in hydrangea flower color.

Propagation methods of hydrangea

1. Division: Division should be carried out in early spring before sprouting. Separate the rooted branches from the mother plant and pot them directly. Do not water too much. Keep them in semi-shade for care, and after new buds sprout, switch to normal care.

2. Layering: Layering is carried out when the buds begin to swell. Roots can grow after 30 days. In the spring of the following year, cut it off from the mother plant, transplant it with soil, and it can bloom that year.

3. Cuttage: Cuttage is carried out during the plum rain season. Cut off the tender top branches, about 20 cm long, remove the lower leaves. The suitable temperature for cuttage is 13-18°C, and roots form 15 days after insertion.

How to grow potted hydrangeas?

1. Soil: The soil for planting hydrangea should preferably be loose, fertile and well-drained sandy loam. For potting, it is advisable to use a culture soil mixed with 4 parts leaf mold, 3 parts garden soil, 2 parts river sand and 1 part cake fertilizer, or a mixture of 4 parts compost soil, 5 parts sandy soil and 1 part cake fertilizer, or a mixed soil of 6 parts leaf mold, 3 parts sandy soil (or cinder) and 1 part cake fertilizer. After potting, water thoroughly, keep it indoors for care, and move it outdoors in early May.

2. Watering: Hydrangea leaves are relatively large and require more water. In spring and summer, water frequently to keep the potting soil moist. In the hot summer, water once in the morning and once in the evening, and pay attention to proper shading. In winter, water less, as long as the potting soil moisture is maintained. During the growing period, watering should be sufficient so that the potting soil often remains moist, especially in summer, when even more sufficient water should be given.

3. Light: Hydrangea is a short-day plant. After being moved outdoors in spring, it should first be placed in a semi-shaded environment for care. In midsummer, move it to a well-ventilated shady place to prevent leaf sunscald. After September, the light intensity gradually weakens. To promote flower bud differentiation, move the pot to a place with more light.

4. Temperature: Hydrangea likes a warm environment. The optimum growth temperature is 18-28°C, and the winter temperature should not be lower than 5°C. Flower bud differentiation requires 6-8 weeks at 5-7°C. A temperature of 20°C can promote flowering, and maintaining 16°C after flowering can extend the viewing period. Note that high temperatures make the flowers fade quickly.

5. Fertilization: Hydrangea likes fertilizer. During the growth period, generally apply a dilute cake fertilizer water once about every 15 days. To keep the potting soil often acidic, add 0.2% ferrous sulfate when applying liquid fertilizer to make it into alum fertilizer water for irrigation. During the bud stage, apply 1-2 additional applications of 0.5% superphosphate soaking solution, which can promote larger flowers and brighter colors.

6. Pruning: In early spring each year in March, cut off diseased, dead and weak branches from the base of the hydrangea, retain 3-5 strong main branches and shorten them, leaving 2-3 buds on each branch to promote new branches and make it bloom abundantly. Through pruning and shaping, the tree shape can be made compact, full, symmetrical, with more flowers, larger blooms and brighter colors. If not pruned, the base of old branches over 3 years old has become woody and is not easy to sprout new branches, which easily forms a hollow lower part of the plant and affects ornamental value.

7. Pests and diseases: The main diseases of hydrangea include wilt disease, powdery mildew and leaf spot disease, which can be prevented and controlled by spraying 65% zineb wettable powder at 600 times dilution. The main pests of hydrangea are aphids and mirid bugs, which can be killed by spraying 40% omethoate emulsifiable concentrate at 1500 times dilution.

Precautions for hydrangea

1. Hydrangea likes acidic soil and cannot tolerate barren or saline-alkaline soil. It grows poorly in alkaline soil, with yellowing branches and leaves, and is suitable for loose, fertile acidic soil rich in humus. Its flower color is affected by pH and can change from white to red, and from red to cyan-blue.

2. Move hydrangea indoors in early to mid-October. Control watering and keep the room temperature at about 5°C to promote dormancy. Before moving indoors, remove the leaves to avoid leaf rot. Starting in mid-December, move it to a sunny place and maintain a temperature of 15-20°C to promote the growth of branches and leaves, and move it outdoors in late April of the following year.

3. For hydrangea seedlings cuttings made in March, after rooting they can be moved into 10 cm pots, and in mid-June they can be finally planted in 16 cm pots. Perform the first pinching in June. If pinched in early June, flower buds can form in mid-August. Seedlings cuttings made in May-June can be finally planted in 16 cm pots in July-August. To promote flower bud formation in the same year, the last pinching must be done before September, otherwise flower buds cannot form that year.

4. Hydrangea likes fertilizer. During the growth period, generally apply a decomposed dilute cake fertilizer water once every 15 days. To maintain soil acidity, 1-3% ferrous sulfate can be added to the fertilizer solution. Regular irrigation with alum fertilizer water can make the plant lush with branches and green leaves. Applying 1-2 additional applications of monopotassium phosphate during the bud stage can make the flowers large and brightly colored. Applying cake fertilizer should avoid the dog days to prevent pests and diseases and damage to the root system.

5. Hydrangea leaves are large and the branches and leaves are luxuriant, so it requires more water. In the growing seasons of spring, summer and autumn, water sufficiently to keep the potting soil often moist. In summer, the weather is hot and evaporation is high. In addition to sufficient watering, spray water on the leaves every day. The roots of hydrangea are fleshy roots, so watering must not be excessive. Do not allow water to accumulate in the pot, otherwise the roots will rot.

6. After September, as the weather gradually turns cooler, gradually reduce the amount of watering for hydrangea. Before Frost's Descent, move it indoors, and the room temperature should be maintained at about 4°C. Before moving indoors, remove the leaves to avoid leaf rot. In winter, it is advisable to place the plant in a sunny indoor place, and it is suitable to move it outdoors after Grain Rain in the following year. Hydrangea management is relatively extensive, with few pests and diseases, and it is an ideal potted flower that is relatively easy to manage and cultivate.