Leaf pruning is primarily applied to deciduous trees that have beautiful branches and leaves, for example Acer (Maple), Zelkova, Beech, and Hornbeam. Leaf pruning achieves the same effect as pruning the other parts of the tree in increasing the number of small branches and leaves. In addition, it improves the sunshine and ventilation for young buds and small branches between the leaves to promote their growth. This also helps to bring out clearer view of the tree's shape and the inside of the tree, and it makes branch pruning and bud pruning smoother to carry out. Leaf pruning allows the lateral buds to stretch and grow and thereby promotes the growth of new branches and leaves. In this way, it takes only one year for the tree to develop the branches and leafage that would otherwise require two years. Moreover, the new branches and leaves are small for they have only been growing for a short period. Even if the leaves suffered from pests, you can grow new leaves by leaf pruning.
Leaf-pruning the whole tree - Zelkova
Partial leaf pruning―Acer(Maple)
Partial Leaf pruning―Japanese maple
Cutting off part of each leaf― Zelkova
Cutting off part of each leaf ―Japanese maple
How to carry out leaf pruning depends on the purpose, the condition of the tree, and the species of the tree. For example, for young trees and those still under bonsai making, you can prune all the leaves to increase the number of small branches and leaves.
If you want to adjust the length and the shape of a plant that is more or less completed, you only need to prune the tree top and the well-developed portion on the outer side.
Alternatively, when you want to maintain the tree's vitality, for leaves that grow in pairs (opposite phyllotaxis), it is enough to prune the leaf on either side.
If you want to improve the sunshine and ventilation on the inside of the tree, but the tree has developed its shape and does not need new branches or leaves, you can cut off each leaf by half. Of course, you can make comprehensive use of all the above-mentioned methods.
Each tree species has its own properties. Take the Japanese maple for example, it tends to grow lateral buds especially well after pruning. If the tree already has a completed shape, it’s delicate beauty will be disturbed by the new branches grown from the lateral buds. So a careful management of the tree after leaf pruning is necessary. If you apply leaf pruning to the whole or a part of a beech tree, new leaves may grow in undesired shapes. So you typically need to cut off each leaf by half or by a portion in order not to make the new leaves come out. Since the tree needs to bud after you prune all the leaves, the best time to carry out leaf pruning is typically between late spring and early summer. If you only prune part of the leaves, then you should do so between late spring and early autumn when plants stop growing. If you only cut off each leaf by a portion, then the best time to do so is during late spring and summer. Like other pruning, leaf pruning brings heavy burden to trees. You need to fertilize the tree before each leaf pruning to maintain its vigorous growth. After leaf pruning, you should reduce the amount of watering based on the amount of leaves pruned. You must not fertilize the tree before the new buds grow out. In addition, if you prune all the leaves, you better place the tree in a shaded bright area for approximately ten days after pruning.
“For many species of deciduous bonsai trees the size of the leaf is directly related to the type and amount of sunlight the tree is cultivated in. A bonsai that is grown in partial shade or in full shade will have longer and larger leaves, because the tree is trying to maximize the amount of sunlight it can absorb to enable it to continue its photosynthetic processes - a larger leaf has more surface area with which to gather sunlight. In contrast, a bonsai tree that is grown in direct sun, all or most of the time, will have smaller and more compact leaves, because it is receiving all of the sunlight it needs. As a result, it can devote its energy to growing. This is important for all trees, but more important for trees cultivated for bonsai, as smaller leaves are proportionate to the smaller scale of a bonsai tree; smaller leaves are, therefore, a positive trait, both aesthetically and from a horticultural perspective, because a tree is healthiest when it has access to all of the energy it needs to develop.”
“An evergreen tree, such as a pine (black, white, red, scots pine, etc.) does not keep its needles forever. In fact, while evergreen trees do not shed their needles in a blaze of autumn splendor, along with the deciduous trees, every fall, they do replace their needles in two or three year cycles. Accordingly, evergreen trees remain for the most part, always green, because younger needles remain on the branch, as more mature needles are replaced.”
The Size of The Leaf and Sunlight
“Have You Ever Wondered Why Leaves Change Color? The answer to that perplexing query begins with this question: what are leaves? Leaves have been dubbed as: nature's food factories. During the spring and summer leaves serve as factories where a large amount of the foods necessary for the tree to grow are manufactured. The process that trees utilize to turn water and carbon dioxide into sugar is called - photosynthesis. A chemical called - chlorophyll - enables photosynthesis to take place. Chlorophyll is what gives leaves their green color. Along with the green pigment of chlorophyll, there are also yellow and orange pigments - carotenes and xanthophylls - that, for example, give the orange color to carrots. However, most of the year these colors are masked by the large amounts of green coloring from the very busy chlorophyll.” “Why Does this Change Occur? As summer ends and autumn begins the days progressively become shorter and the amount of light that trees receive is reduced. Along with the changes in daylight hours, overall temperatures become cooler. It is these two principal changes that ‘tell’ trees the time to begin getting ready for winter has arrived. Trees start preparing for their winter dormancy by shutting down their food-making factories, their leaves. The reason they do this every year at the same time, is because there are not enough hours of daylight for photosynthesis to take place. When the leaves stop their food-making processes, the chlorophyll begins to diminish. The prominent green color of the leaves dwindles, as the yellow and orange colors permeate the leaves, giving them their celebrated fall grandeur.” “Do Other Changes Occur At This Time? As the traditional fall colors emerge, additional chemical changes occur, resulting in the development of anthocyanin pigments. These pigments produce of a bonus number of brilliant colors ranging from red to purple. Cool temperatures - above freezing - favor the formation of anthocyanin, thus producing bright red leaves on maples and deep purple leaves on dogwoods and sumac trees. Temperature, light, and water supply all have an influence on the degree and duration of the colors of autumn. Rainy and overcast days have a tendency to amplify the intensity of fall colors and an early frost can weaken the brilliant colors of fall.” “It is the combination of all these things that create the striking colors we enjoy so much every fall. The mixtures of yellow, orange, red, and purple are the result of chemical processes that take place inside the tree as, outside, the seasons change from summer to autumn and then to winter. One of my favorite ways to enjoy the awesome colors of autumn is with a big bag of candy and my favorite Halloween costume. Trick-or-Treat!” By Tom Regan