What Is Defoliation?
In a nutshell, defoliation is the careful removal of healthy leaves from your bonsai. You practice defoliation to induce a new flush of growth. Only carry out defoliation in the growing period and on mature deciduous trees that are strong enough to withstand the procedure.
Defoliation is an intricate, time consuming and advanced technique that carefully strips some or all of the leaves from your bonsai tree. The intentional trimming encourages the growth of new, smaller leaves and encourages further development of the tree. Interestingly, defoliation stimulates new growth twofold in the next period of growth.
You will need to carry out this delicate procedure in the summer months.
Although defoliation is primarily used to reduce the leaf size, it also causes ramification.
Ramification forces the tree to have more branches so that the distribution of energy is interrupted and imbalanced, which results in the leaves receiving less energy, thus making them smaller. The branches begin to taper and have finer tips which also has the side effect of smaller leaves.
Why Defoliate A Bonsai Tree?
Bonsai is the practised art of precision. The various techniques that create aesthetic pleasure, harmony and balance have been advanced over centuries. You can implement various bonsai rules and techniques to aid growth rate and regulate shape.
In short, the art of bonsai is to grow a full-scale tree in miniature form. Not only are you making the overall tree and branches much smaller, but you should also produce smaller leaves to keep them in scale. Full-scale leaves will spoil the perspective of the tree hence the need for defoliation to help reduce the size.
By encouraging ramification, you will encourage additional, smaller branches.
The defoliation technique is an advanced technique used by bonsai specialists to encourage trees to grow smaller leaves. This process will encourage the tree to flourish and grow new healthy sprigs. You should only practise this technique on deciduous bonsai; trees that respond particularly well are elm, hawthorn, beech, oak, fig and maple. Defoliation should not be carried out on evergreen specimens.
You can also defoliate on a specific area of your bonsai to promote needed growth for the best overall aesthetic. Defoliation can also produce more vibrant autumnal colours.
Partial Vs Complete Defoliation
Partial defoliation is probably the best way to start.
Partial defoliation has many benefits and dramatically reduces the risk of the tree dying due to critical mistakes, which unfortunately are commonplace with complete defoliation. The various species and specimens will react differently, so it is wise, particularly if you are a beginner, to start with partial defoliation so that you can keep the tree healthy by regularly assessing how it is responding.
By using the partial process, you can easily shape the tree in sections and, over time, restore the aesthetics of your bonsai. You might want to encourage the growth of smaller leaves at the very top of your tree to give it a more realistic and authentic appeal.
If you are looking to encourage general growth, by removing the outer leaves, you will allow more light to the inner leaves, promoting more growth. This procedure can be used throughout the tree’s life to maintain a healthy, well-balanced appearance. You can remove larger leaves throughout the growing season, and tiny leaves will replace them towards the end of the summer.
The best time to carry out complete defoliation is in June, when the leaves have hardened, become tougher, and are a beautiful dark green. One of the most important benefits of complete defoliation for experienced bonsai experts is that it allows them complete access and control of the tree. By having no leaves present, they can really concentrate on the wiring and shaping of the tree.
Partial defoliation gives your tree much less of a shock, so it is less likely to die. The great thing about regular partial or complete defoliation is that the more the tree grows, the more opportunities there are to wire, train and shape the bonsai.
When To Defoliate A Bonsai Tree
It’s important to remember the various stages that your bonsai goes through each year. The summer is the growing season, and the spring, autumn and winter are the resting seasons when your tree goes into dormancy. Dormancy is an inherently inbuilt strategy that temperate climate bonsai have evolved to stay alive in the winter. They have a biological clock that prepares the soft tissues for cold or freezing temperatures.
The ideal time to partially or wholly defoliate a tree is when the new spring growth has hardened, which, depending on species, will be in May or June. May tends to be the right time to defoliate oak, fig, elm, hawthorn and privet. Hornbeam, crabapple, fushia and maple are best suited to June when the leaves are actively growing.
REMEMBER: Check Your Tree Health!!
Partial or complete defoliation of your bonsai is very hard on your tree and can cause intense shock. By intentionally limiting the growth of your tree, you will temporarily weaken the bonsai. Study the tree before you start; any weak-looking branches should be left alone to bud, grow leaves and get more vital for the following season.
If you have recently re-potted or heavily pruned your tree or it has suffered from a recent disease, don’t defoliate your tree. Perfecting a bonsai requires endless patience!
In some cases, defoliation can be harmful to a bonsai tree. Not only should they be healthy, but it’s known that bonsai trees that produce fruit don’t respond particularly well. Certain ficus species can also exhibit branch dieback; sometimes, leaving a few leaves on a branch can reduce the risk. You should also realise that the defoliation process tends to halt the growth of a tree temporarily.
Trees naturally gather their nutrients, moisture and oxygen through photosynthesis. This chemical reaction takes place inside the leaves of a plant, producing food for the plant to survive. Carbon dioxide, water, and light are all needed for photosynthesis to take place.
If you are still learning about the defoliation technique, it’s wise to tackle between a quarter and a third of the tree at a time until you gain confidence and experience.
How To Defoliate A Bonsai Tree: Step By Step Guide
Once you have assessed your tree to ensure that it is a suitable specimen, the right species, and it is in healthy condition, you can start to prepare and plan the defoliation of your tree carefully.
You must always ensure that your tools, leafcutter or pruning scissors are clean and sharp. Plan which area of the tree you will partially defoliate, then carefully prune the leaves and allow the stems to remain intact.
Step 1: Check If Your Tree Is Suitable
The primary consideration in deciding if your tree is suitable is the type of tree.
Evergreen trees such as pine, juniper, Japanese holly, pistachio, sageretia and podocarpus are not suitable for defoliation. However, deciduous bonsai trees like elm, hawthorn, beech, oak, fig and maple work beautifully. You must ensure that your deciduous tree is not compromised in any way by disease, recent re-potting, pruning or are young trees that are still in training.
Step 2: Get The Right Tools
The right tools are essential to ensure a clean, healthy cut that will heal well. You don’t want to cause additional shock with blunt or dirty blades, which can cause damage or infection. Make sure that your blades are sharp and have been cleaned thoroughly with rubbing alcohol or antiseptic. You may be able to pinch out leaves and buds with your fingers.
Have some bonsai cut paste to hand in case you slip and mistakenly cut the wood.
Step 3: Locate The Defoliation Area
You will need to assess the areas that you would like to defoliate carefully. For example, if you want to encourage growth to an apically dominant tree, you will choose to defoliate the top of the tree. As you encourage more growth, you will have more opportunities to shape and train your bonsai.
Locating the correct defoliation area is essential and should be well consudered and planned.
Step 4: Prune The Leaves
Begin by carefully clipping the large leaves at the end of the branch tips.
By removing these larger leaves, you will allow more light to reach the smaller branches at the centre of the bonsai and the lower parts of the tree. Partial defoliation will stimulate vigorous growth. You can use your fingers to prune the soft leaves or for more rigid leaves, use a leafcutter or twig shears. Ensure that you leave the leaf stem intact. If you are entirely defoliating the tree, continue until all of the leaves are gone.
You’ll now notice the real structure of the tree, which will help you plan for future defoliation, pruning and training.
Step 5: Aftercare
There isn’t too much aftercare that you need to consider other than regular but slightly less water; after defoliation, there are fewer leaves that require nourishment. Ensure that you keep the newly trimmed bonsai out of the full sun. The inner leaves are now exposed and will need to become hardier before they are placed in the sun to avoid burning.
In three to six weeks, you’ll begin to notice new buds appearing, and the new tiny leaves will gradually start to unfurl. The leaves will be smaller as they have had less time to develop in the growing season.