A Detailed Guide to the Latest Hydrangea Growing Methods
The proper name of the hydrangea is wax flower (Hoya), also known as eight-immortal flower, purple sun flower, seven-transformation flower, foreign hydrangea, and powder-ball flower. It originated in the Sichuan region of China and Japan. It is a deciduous shrub of the order Cornales, family Hydrangeaceae, genus Hydrangea. Its flowers are almost entirely sterile flowers; the so-called “flowers” are merely sepals. China cultivated the eight-immortal flower relatively early; hydrangeas were planted in the Jiangnan gardens built during the Ming and Qing dynasties. Parks built in the early 20th century also could not do without hydrangea plantings. Modern parks and scenic areas plant them in masses to form landscapes. Artificially bred hydrangeas have large flowers and brilliant colors, with flower colors including blue, white, purple-red, pink, and peach-red. It is a common ornamental flowering shrub.
Growth Habits of the Hydrangea
We must first understand the growth habits of the hydrangea in order to master hydrangea growing methods in a targeted way. The hydrangea originates from China's Yangtze River basin and prefers a warm, humid, and semi-shaded environment. It fears both drought and waterlogging, and is not cold-tolerant; in cold regions its aboveground parts die in winter and do not sprout new shoots again until the following spring. The hydrangea likes fertile, moist, well-drained light loam and has relatively strong adaptability. The acidity or alkalinity of the soil has a considerable effect on the flower color of the hydrangea: in acidic soil it is mostly blue, and in alkaline soil it is mostly red.
Propagation Methods of the Hydrangea
Commonly used methods are cuttings, division, layering, and grafting, with cuttings being the main method. During the plum rain period, select robust young shoots from a young mother plant as cuttings; the base of the cutting must include a node and be dipped in mud slurry, about 20 cm long, with the lower leaves removed. The suitable temperature for cuttings is 13-18°C; after inserting, shade is needed and moisture must be maintained frequently. Roots develop in about 15 days to 1 month, and after surviving, they can be transplanted in the second year. Division propagation should be carried out before sprouting in early spring. Separate the rooted branches from the mother plant and pot them directly; do not water too much, and care for them in semi-shade. After new buds sprout, switch to normal care. Layering propagation can be carried out when the buds begin to swell; growth occurs after 30 days, and the following spring it is cut from the mother plant and transplanted with soil, and it can bloom that same year. Generally, air layering is done in spring from March to April, roots form in June to July, and it can be cut off and planted separately that same year. For grafting propagation, use seedlings of Viburnum macrocephalum as rootstock and do cut grafting in spring; it survives easily. Transplanting should be done after leaf drop or before sprouting, and the soil around the roots must be kept. The main branches tend to sprout leggy shoots, so after flowering they need proper pruning to tidy the tree shape.
Cultivation and Management of the Hydrangea
The suitable growth temperature for the hydrangea 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 flowers appear can prolong the viewing period. However, high temperatures make the flowers fade quickly. The hydrangea is a short-day plant; with more than 10 hours of darkness per day, flower buds form in about 45-50 days. Potted hydrangeas commonly use 15-20 cm pots. After potted plants sprout in spring, pay attention to watering thoroughly to ensure the leaves do not wilt. During the flowering period from June to July, fertilizer and water must be sufficient, with fertilizer applied once every half month. In ordinary cultivation, avoid direct sunlight; 60%-70% shading is ideal. When the light is too strong in midsummer, appropriate shading can prolong the viewing period. After flowering, remove the flower stems to encourage new branches.
The soil is best if it is loose, fertile, and well-drained sandy loam. But flower color is affected by soil acidity and alkalinity: acidic soil produces blue flowers, and alkaline soil produces red flowers. 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 plants are better kept slightly dry. If too humid, the leaves rot easily. Repot once every spring. Prune properly to keep the plant shape attractive.
Potting and Pruning of the Hydrangea
Hydrangea propagation is suitable in spring and autumn, but late spring and early summer (late April to July) is best. At this time, the hydrangea flowering period has basically ended in May; after removing spent flowers and withered leaves and pruning, new branches, leaves, and buds have grown, and the top branch buds can be cut as cuttings. Cuttings can also be done in late September to October. In early spring, after the hydrangea is pruned and the top buds are taken as cuttings, many new branch and leaf buds sprout again; because the weather has turned cooler at this time, it is suitable for cutting propagation.
1. Besides seedbeds made of brick, for easy movement and management, a foam box can be used as a seedbed. First cut a few openings in the bottom of the box, then cover the openings with tile pieces, fill in a layer of coarse sand, and then add culture soil (3 parts sand, 2 parts sterile mountain soil, mixed evenly); level it and it is ready for cuttings. Cut the cuttings into 10-15 cm sections, remove the lower leaves of the terminal shoots, and keep only 2-3 leaves at the top. After cutting, tie the cuttings and smooth them out. To help the cutting wounds heal and take root sooner, soak the smoothed cuttings in a strong rooting agent (about 0.2 kg of water per packet) for 5-10 minutes before inserting them. After inserting, press the soil around the stems firmly with your fingers so the cuttings are tightly combined with the soil. Then water thoroughly once with a watering can. After that, as long as the seedbed soil is moist, there is no need to water, but frequently mist the cutting leaves and keep the environment around the seedbed moist. If the weather is hot and the sunlight is strong, a shade shed must be built for shading. Under such careful management, in about 25 days the wounds begin to heal and new roots grow from the nodes.
2. Potting and cultivation care: After about 25 days of careful management, the hydrangea has survived and new leaf buds begin to grow upward from the top bud; at this point it must be planted separately in pots for management. The culture soil for cultivating hydrangeas uses coniferous soil (relatively high in acid) plus bran matter, nitrogen, phosphorus, and potassium (according to the amount of coniferous soil) compound fertilizer mixed with soil, piled and fully fermented for more than half a year, then spread out to air and dry for several days before use. After the seedlings survive and the top branch grows to about 10 cm, the first pinching can be done to encourage new leaf buds to sprout from the lower part; when the several branch buds that grow later reach a certain length, do the second pinching, and let them grow evenly and lushly. When the main trunk and branches are thick and strong, leave only 3-4 branches and let them grow freely. From potting and survival to branch setting, fertilizer needs to be applied 3-4 times, mainly potassium dihydrogen phosphate.