What are the winter care methods for deciduous bonsai?

In the first month of the new year, temperatures in the south have hit bottom, and combined with the recent long period without precipitation, these conditions bring quite a few troubles for plant care. Although Shanghai-style bonsai is most famous for pine species such as Japanese white pine, the number of deciduous bonsai at Shanghai Botanical Garden is also considerable. How these deciduous bonsai are cared for in winter is crucial to their growth in the coming year.

The so-called deciduous trees are naturally rather "mixed," which is reflected in the varieties: Chinese elm, Chinese plum yew, ginkgo, crape myrtle, star jasmine, pomegranate, trident maple, wild lacquer tree, and so on - whatever should be there is there, varying according to the characteristic tree species of each region. Although deep winter in the south is cold, most deciduous bonsai can still overwinter outdoors. Many people move their bonsai back indoors at night to protect them from freezing, but be sure to remember to take them back outside during the day; if conditions are limited, at least place them on the windowsill in the sunniest spot and ensure sunlight during the sunniest hours at noon. Many trees develop yellow leaves in winter because of a lack of light indoors. Since noon temperatures are relatively high, it cannot be ruled out that excessive warmth may prevent deciduous bonsai from entering dormancy or cause them to wake early, which is also harmful. Under extreme climates with temperatures higher than the average winter temperature of previous years for extended periods, local climate conditions also need to be temperature-controlled.

Shanghai is located on the southeast coast, where outdoor winds are strong and exacerbate the dryness of the air. Because watering is reduced in winter, bark and branches may become shriveled if one is not careful, and more seriously, fruit-display bonsai such as Diospyros rhombifolia, gold bullet tree, black bamboo, firethorn, and cotoneaster may even show dehydration of the fruit. Observing the potting soil regularly is extremely important. Generally, noon in winter is the best time to water. When the potting soil turns white, water thoroughly in one go - never water a little at a time repeatedly. In the current extremely dry climate, moderately misting the trunk and branches is also a good way to ease the problem.

Usually, if deciduous bonsai are pruned in early autumn, they will sprout again, and the resulting leaves generally will not drop in winter, as with Chinese elm bonsai; if the tree is growing weakly, it is better to prune during the winter-spring bud-break period. Due to seasonal influences,

deep winter is not suitable for repotting, as it greatly harms the roots of deciduous bonsai, weakens their cold resistance, and makes them prone to dying.

By paying attention to the most important measures such as water control, insulation, and supplemental light, overwintering deciduous bonsai safely is not that difficult. As tree species that provide the skeletal structure for winter viewing, every branch of a deciduous bonsai holds the promise of spring and is a beautiful continuation of life. However, it is worth reminding that cold-tender deciduous bonsai such as sago palm, banyan, Fukien tea, and orange jessamine - typical southern tree species - are still best kept indoors for overwintering care.

Winter care and management of ancient stump bonsai

Key points for winter care of small chrysanthemum bonsai

    After old small chrysanthemum bonsai plants are lightly pruned following flowering for rejuvenation, different methods can be chosen for overwintering depending on region and weather conditions. In southern and central China, there is no need for elaborate covering against cold in winter; simply place the bonsai against a south-facing wall that is sheltered from the wind and exposed to light. In rainy areas, moderate protection against waterlogging is enough to pass the winter cold safely. In mild areas of northern China, small chrysanthemums need slight covering for overwintering; as long as the coldest temperature does not fall below -10°C, the chrysanthemum plants will not freeze to death. In northern and plateau regions, frost is severe. The frost period is long, and nighttime temperatures drop to -15°C or even lower, so soil burial is generally used. Methods such as burying the lower part in soil while covering the upper part with dry leaves, placing them in cellars, cold rooms, or lower-temperature greenhouses are used to avoid the cold winter. Here, the prohibitions in protection and management during the overwintering process of small chrysanthemum bonsai in the north and plateau regions are introduced for everyone's reference, so as to avoid losses caused by improper handling by friends who are new to growing small chrysanthemum bonsai.

    The roots and root buds of small chrysanthemums have relatively strong cold resistance and can generally endure freezing at -30°C; the old stems, leaves, branches, and buds above the root zone are all difficult to keep unharmed below 0°C. That is why we commonly see chrysanthemum plants dry up above the soil in winter, while root buds grow when spring warms. With reasonable management, small chrysanthemum bonsai that we have grown for a year can not only bloom the next year, but after scientific pruning control and wiring for shaping, the whole plant grows larger and denser, blooming even more and better than the previous year. Below, the management prohibitions are discussed separately according to the overwintering methods mentioned above.

    Soil burial, or burying the lower part in soil while covering the upper part with dry leaves. Before the frost period arrives, small chrysanthemum bonsai can be buried with or without pots; plain wet soil should be used for burial and covering. First, it is forbidden to use fertilized soil or soil mixed with firewood, grass, or leaves, because plain soil will not mold or generate heat that harms chrysanthemum roots and plants. If plain wet soil is used to bury the lower part and dry leaves are then used to cover the upper part, even if the leaves become wet from snow, they will dry in the wind after clearing, causing no major harm to the chrysanthemum plants. Second, it is forbidden to keep watering after burial, because they are already buried in wet soil. Small chrysanthemums sleep under the soil and do not grow or consume water. Even if the soil surface dries, it is only shallowly dry, and the chrysanthemum plants are in no danger of dying from drought throughout the winter. Therefore, excessive water will instead suffocate the slow respiration of the chrysanthemum plants, causing death and rot. Third, it is forbidden to dig them up to check. During hibernation, chrysanthemum plants gradually adapt to the small environment, and there is no need to inspect or check on them. Digging them up first easily cuts and injures chrysanthemum stems and branches, and improper reburial can also cause the plants to overheat or freeze. With this storage method, it is best to do it carefully and thoroughly at the beginning, then confidently leave them alone until spring.

    Entering a cellar or cold room. Small chrysanthemum bonsai can also overwinter in a cellar or cold room with or without pots. If unpotted and placed in a cellar or cold room, the roots must still be buried in wet soil, and the upper part may be covered or left exposed, but the ambient temperature must not be lower than -10°C. The ideal temperature is -4°C to 4°C, maintaining dormancy until sprouting and growth between February and March in spring. During this period, it is forbidden to let them become too dry and suffer damage or too wet and become waterlogged and rot; at the same time, temperature monitoring of the environment must not be neglected. Forgetting to cover the cellar opening or forgetting to close doors and windows, causing cooling and freezing, or sporadic high temperatures in the cellar or room forcing out tender buds, are both harmful to the chrysanthemum plants. Generally speaking, plants placed indoors are prone to becoming too dry and need water supplementation, but do not water frequently. When placed indoors and encountering warm sunny weather, the temperature can also rise easily, but when opening doors and windows, be sure not to forget to close them again in time.

    Entering a lower-temperature greenhouse. Chrysanthemum plants will stop dormancy in early winter and shift into a growth state. In this situation, management must be carried out, and it is forbidden to let them grow wildly unchecked. New buds should be reasonably thinned and retained, and long branches should be pruned or wired and bent, that is, entering shaping management.

    Avoiding the prohibitions above can enable old small chrysanthemum plants to go robustly from dormancy to growth, and in the coming year the chrysanthemum plants will enter autumn again larger and stronger, contributing glory once more.