By: Bonnie L. Grant, Certified Urban Agriculturist
Dreamy gardeners often view their landscapes as living art. Arborsculpture techniques can make those fantasies come true by providing form and eco-art in its purest form. What is arborsculpture? It is a series of gardening practices that combine grafting, bending, and training of living plants, usually trees. The techniques require time and expertise but even a novice can perform simple arborsculpture methods for unique, personalized living garden art.
What is Arborsculpture?
You may think that a living tree sculpture is an impossible dream but professional arborists and eco-artists have perfected the techniques for centuries. Formal gardens of the past used to include many forms of plant training, from espalier to topiary. Tree training arborsculptures is simply a larger project using those techniques as well as grafting and pleaching. The finished project may take years or even decades, so it is not a task for the impatient.
Arborsculpture gardens allow the imagination to run wild and one’s inner child to come out to play. There are many classic forms of tree shaping but almost anything may be made. Some examples of the practice include living chairs or even a boat. The shapes are developed over time with careful training and grafting as well as knowledge of how the chosen tree species tend to grow.
Modern interest in the craft spiked in the late 1940s when Axel Erlandson became fascinated with tree shaping and eventually went on to shape nearly 70 trees into intricate knots, curves, spirals, zigzags, and other forms. The location was known as Axel’s Tree Circus and was a famous tourist destination until his death.
Arborsculpture Techniques and Tools
Tree training arborsculptures is a demanding practice. You must start with young trees when the branches are still pliable.
- One of the main techniques is grafting or joining 2 pieces of living plant material together so that they grow into a single plant. The technique allows new material to join the main trunk and create specific curves or angles.
- Another procedure is espalier, which combines simple training methods like staking and tying with the knowledgeable direction of side shoots and main stems.
- Bonsai and topiary art forms are also included in a living tree sculpture.
The tools necessary are stakes, string or twine, wire, tree tape, pruners, saws, loppers, and sometimes a chainsaw. For grafts, you may need to do bridge grafts or simple grafts called approach grafts.
If you are tempted to try this method yourself, you will need to do some planning. Choose your tree carefully. Plants that grow quickly will allow the finished product to come to fruition more rapidly but they also require constant vigilance to prevent errant growth that will spoil the end result. A tree with moderate growth allows you the time to investigate the form and make adjustments as needed. Unbranched 6- to 8-foot (2 to 2.5 m.) tall saplings are ideal. Some of the most popular trees to use are:
- Box Elder
- Cork Elm
- Japanese Maple
- Weeping Willow
Next, you will need to write out a plan for your design. Take into consideration the natural growth pattern of the plant and see what you can do with that for a simpler beginner project. Plant the tree or trees in an ideal location for good growth.
Now begins the grafting process, which will begin to shape the tree into the forms you desire. You can also begin by simply bending the branches into the shapes necessary to develop your design. This is the easiest approach unless you are versed in grafting. Use stakes, cables, twine, etc. to help the branches stay in place as they are trained.
As you can see, arborsculpture gardens don’t come about overnight. It takes years of patience and toil to see the fruits of your labor in their full glory but the process will be instructive, creative, and fun.
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Read more about General Tree Care
An espalier (pronounced “es-PAL-yer”)is a plant that has been trained to grow in a flat plane against a wall,fence, or trellis, though the term has also been used to describe the technique of training a plant to grow this way.
The technique was invented by the ancient Romans, and further developed in Europe. This technique allowed them to take advantage of the thermal mass of south facing walls (full sun in Northern Hemisphere) by growing fruit trees against them, the heat retained by the walls protected the trees from the cold and extended the productive period of the of fruit trees.
As the technique eventually became an art form in itself, the trees became a kind of living sculpture, and many ornamental trees and plants were also used as espaliers.
The main benefit of the technique of growing espaliered trees is that they save a lot of space. You can grow a productive tree in a space that would otherwise be too narrow to be of use, or you can line up trellises in an open area, a few feet apart, running north to south so they dont shade each other, to create a very high density espalier orchard. Espaliers have also been used to create living fences. A fruit bearing fence fits in with the permaculture principle that “everything has more than one purpose or function” very nicely.
You can virtually grow any plant as an espalier, it’s just a matter of maintaining a two-dimensional form by training all growth along a flat plane and pruning away any growth that can’t be laid flat because of the direction it’s growing.
Some plants are particularly suitable as espaliers. Plants that produce many flexible lateral branches and attractive flowers, fruit, and foliage and/or bark are excellent choices for espaliers.
Plan Approach to Pruning
Pruning should follow a definite plan. Consider the reason or purpose before cutting begins.
By making the pruning cuts in a certain order, the total number of cuts is reduced greatly. The skilled pruner first removes all dead, broken, diseased or problem limbs by cutting them at the point of origin or back to a strong lateral branch or shoot. Often, removing this material opens the canopy sufficiently so that no further pruning is necessary.
The next step in pruning is to make any training cuts needed. By cutting back lateral branches, the tree or shrub is trained to develop a desired shape, to fill in an open area caused by storm or wind damage or to keep it in bounds to fit a given area. To properly train a plant, one should understand its natural growth habit. Always avoid destroying the natural shape or growth habit when pruning unless maintaining a close watch over the plant, for after a period of time it attempts to assume the more natural growth habit.
Make additional corrective prunings to eliminate weak or narrow crotches and remove the less desirable central leader where double leaders occur. After these cuts have been made, stand back and take a look at your work. Are there any other corrective pruning cuts necessary? If the amount of wood removed is considerable, further pruning may need to be delayed a year or so. Remove water sprouts unless needed to fill a hole or to shade a large limb until other branches develop.
Training a single stemmed tree
Training in year 1
In the first year of growth allow the tree to grow naturally, not removing any shoots or leaves unless they die or become damaged or diseased. In the winter, select a strong, more or less upright stem to become the central leader of the tree. Stake the stem to a cane which is significantly taller than the tree (so you can continue to use it as the tree lengthens). Ensure that you don’t damage the roots when inserting the cane (either insert the cane before planting the tree, or gently move the soil aside so you can avoid the roots if the tree is already in the ground) and tie the stem to it wrapping the twine around in a figure of eight so the stem won’t rub against the cane. Leave the ties loose enough to allow a bit of movement by the stem. If the central leader’s not growing very well, cut it back to a strong bud, which should then produce vigorous growth to be trained as the leader the following year.
If the leader already has strong lateral growth, shorten this to ensure it doesn’t become dominant over the central leader.
Training in year 2
Continue to prune out any dead, diseased or damaged growth, or any vigorous stems which are competing with the central leader, so that you have a single stem dominating the tree (which should then become a strong trunk). Continue to tie the central leader into the cane at 15-30cm intervals.
If you lose the leader (eg due to physical damage) then prune it back to the first available lateral shoot which is growing more or less upright, or a healthy bud if no lateral growth is available, and train this to replace the original leader. If the buds and shoots grow opposite each other, then remove the bud or shoot growing opposite the one you have chosen as the new leader.
After year 2
At this point you need to decide what form the tree is going to take, and tailor the training accordingly. Below are the main options:
This is the easiest tree form to produce as you are allowing the tree to grow naturally. The focus of your training should be on keeping the central leader straight and making sure the tree maintains a balanced shape.
Your pruning should aim to remove dead, diseased and damaged growth, any growth which is crossing or congested, any weak growth, and any stems which appear to be competing with the leader.
The tree should be properly staked until it is well established.
Make sure that neighbouring trees, constructions, the wind or shade do not prevent one side of the tree from growing as well, leading to lop-sided growth. It’s generally easier to remove the cause of lop-sided growth than to continually try to correct it by training.
A feathered tree is a good form for deciduous trees and the principle form used for evergreen trees (where the wind resistance of the heavy canopy can make clear trunks susceptible to snapping in strong winds).
A standard tree has a clear trunk with a crown of branches which either still have a strong central leader (a central leader standard) or where the central leader stops at the top of the trunk and the growth above it is all lateral (a branched-head standard). Alternatively the standard may have a weeping form.
In all three cases the trunk of the tree should be cleared of lateral growth. This should be done over a period of 4 years. In the first year, remove all the lateral growth from the bottom third of the trunk and shorten the lateral growth from the middle third of the trunk (by a half). In the second and third years repeat this process, except that the lateral growth in the middle third should be shortened by two-thirds instead of a half. In the fourth year completely remove all lateral growth up to the required height of the trunk. In future years rub out any growth on the cleared trunk as soon as it appears. Additional training is then required depending on the type of standard tree you require:
- Central leader standard trees
Pruning of the top third of the tree should focus on keeping the central leader straight so it grows up vertically through the crown. Pruning of lateral growth from the leader should be kept to the minimum. Any branches competing with the central leader should be removed. If the leader is lost then a suitable stem should be trained to replace it, if necessary attaching a tall cane to the tree’s stake to keep the new leader vertical while it establishes.
- Branched-head standard trees
This replicates what, for many trees, is the natural process of the central leader gradually becoming less dominant until there is just a framework of branches with no leader. This commonly happens with trees such as oaks. Pruning can speed up this process or to create a branched-head form where the tree would not naturally do this. To create a branched-head tree the central leader stem should be cut back to just above the uppermost of three or four strong lateral branches in the third or fourth year of growth. Any lateral growth which is growing vigorously upwards should also be removed in case this becomes a new leader. In the subsequent years, continue to remove any upright growth which looks as if it may become a new leader and shorten the lateral growth as necessary to balance the shape and give the tree an open-centred crown.
- Weeping standard trees
How weeping trees are pruned depends on whether they are a naturally weeping plant or if a weeping top growth has been grafted onto a different rootstock. If the tree is not grafted, and is a naturally weeping form, then little pruning is required, even if the growth appears to be upright instead of weeping – the top growth often grows upwards before bending over into the weeping form. If the tree is grafted then the weeping growth will all be coming from one point, so it can often become tangled, therefore congested growth or stems growing across others should be removed. Upward growth which shows no sign of bending over should also be removed.
Grafted weeping trees may need to remain staked for much longer than non-weeping forms in order to support the more top-heavy growth.
The Artful Science of Tree Shaping
Dating as far back as the 16th century, tree shaping has been hinted at in paintings and literature but it was not until the advent of Axel Erlandson, the father of modern tree training, that the art form truly flourished. As a young man, Erlandson was inspired by the sight of two conjoined branches in a hedgerow on his property. As a result, he began experimenting, designing and training over 70 different trees into various stunning horticultural and architectural specimens. He then went on to open a roadside exhibition in Scotts Valley, California in 1947, debuting his curiosities in an aptly named ‘Tree Circus’.
What Erlandson had observed and used to great effect, was a natural form of grafting known as inosculation. Rather ordinary, the phenomenon occurs when trunks, roots or branches in close proximity gradually fuse together it can arise within a single tree or neighboring trees of same or different species. Over time, as the limbs grow, they exert pressure similar to the friction between two palms rubbed against each other. This causes the outer bark to slough off, exposing the inner tissue or cambium and allows the vasculature of both trees to intermingle in essence, joining their lifeblood.
Besides grafting, tree shaping also employs pruning, bending, weaving and bracing to create the dramatic loops, twists and knots evocative of the form. Many of the techniques are borrowed from related horticultural practices such as bonsai, espalier and topiary.
The potential of tree shaping for eco-solutions is promising but much of it still remains dependent on the trial and error projects of a few pioneers.
Three Main Methods
There are three main methods to achieving a shaped tree. Aeroponic culture, Instant tree shaping (Arborsculpture) and Gradual tree shaping.
Aeroponic culture grows the roots of the tree in a nutrient mist until they reach a length approximately 2-6 meters at which time the roots are shaped as they are planted.
Instant tree shaping (Arborsculpture) is the practice of using mature trees or whips approximately 2-3 m long, which are then bent into the desired design and held until cast with the next 3-4 years growth of the tree.
Gradual tree shaping starts by creating the framing to support the growing seedlings and then planting 7- 30 cm tall seedlings or cuttings. The new growth is trained along the design pathways for the next couple of years. Then the trees just grow thicker with time.
Most species of trees are suitable for tree shaping but n ot all species are suitable for the creative treatment of the Arborsculpture method , however. Trees to be bent into shape must be flexible, vigorous and easily grafted (thin barks) notable examples being willow, sycamore, poplar, birch and Persian ironwood.
The movement is so recent in fact, that the term Arborsculpture itself was coined only in 1995 by Richard Reames and Barbara Delbol in their book, How to Grow a Chair – the Art of Tree Trunk Topiary . This book gives detailed instructions of the Arborsculpture instant method of bending up a chair and peace sign in an afternoon.
L iving furniture is a popular application so too is the prospect of living houses and landscape architecture. The ability of growing trees to incorporate foreign material such as metal and glass further solidifies tree shaping as a viable green alternative for use in urban design.
One exceptional instance of this type of urban tree shaping lies in Germany. There, architect Ferdinand Ludwig’s Baubotanik, or Living Plant Constructions, showcases the brilliance of botanical engineering at its best. Among his creations are a three-storey willow tower, an osier willow footbridge, and a silver willow bird watching station. The Plane-Tree-Cube Nagold, a building that incorporates live sycamores, is accessible to the public. Hopefully, future plans of a banyan fig-inspired living air bridge will be too.
Ludwig explains, “I came in touch with some historic examples of living architecture while I was a student and was immediately fascinated. The vision is a new way of integrating trees in architectural and urban design.”
Ludwig’s vision has paid off, attracting attention at Archiprix International, a competition that judges projects in urban design and landscape architecture. His work has also won awards for ‘Deutschland, Land der Ideen’ (Germany: Land of Ideas) and ‘Übermorgenmacher’ (Creating the Day after Tomorrow).
Unlike their dead lumber-based counterparts, living architecture continues to combat soil erosion while providing oxygen, sustenance, shelter and habitation. An integral part of the ecosystem, trees can convert carbon into biomass, mitigating the effects of climate change. Even when harvested (essentially killing them), living architecture persists as a source of aesthetic wonder.
When asked how he was able to shape trees, the late Axel Erlandson often replied, “I talk to them”. Indeed, when humanity and nature work together, the results can be mutually impressive. Rather than cutting down trees, tree shaping seeks to cultivate a natural passion for the future of our world and our environment.
Ansel Oommen is an environmentalist, avid gardener and urban forager in New York City. A former student of the Institute of Children’s Literature, he has just finished writing his first book, The Oak Tree, and is searching for a publisher. You can find out more from Absel at: www.behance.net/Ansel
For more information on the three main methods of tree shaping see the work of Swati Balgi (September 2009), "Live Art" , Society Interiors Magazine (Prabhadevi, Mumbai: Magna Publishing and the book Three Methods of Tree Shaping every aspiring tree shaper should be aware of, Peter Cook and Becky Northey, SharBrin Publishing Ptd Ltd. ISBN 978-1-921571-41-1. You can also view a FREE eBook version of The 3 Methods of Tree Shaping.
For more information about Ferdinand Ludwig visit: www.ferdinandludwig.com
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Tree Shaping Techniques
Here are a few general tips on shaping your plants. You’ll find detailed instructions and tree shaping techniques in the guides and kits I’ve mentioned, but here are a few of the most useful tips I’ve found.
- While some trees can be shaped year-round, it’s almost always better to do so in early spring and early autumn. Growth periods start at the beginning of spring and last until a bit into autumn, so try to allow them time to grow and heal undisturbed. They need some weeks to recover if you’re not using something to “seal” cuts. (Succulents, like Jade, don’t usually need assistance and heal quickly.)
- If you do any pruning, the roots will also need some attention. Trimming any part of the plant will result in it trying to compensate elsewhere, so if you prune, you also need to tend to the roots before they grow too much. It’s all about balance!
- If you’ve ever seen bonsai at larger chain nurseries/outdoor stores, you’ll notice a lot of scarring. This often comes from wires being left on, unadjusted, which cuts into the tree over time. This is not a typical practice and is undesirable in bonsai of any kind. So if you’ve been turned off of bonsai due to the state of trees like this, just know that’s not how they’re supposed to look! Keep an eye on your tree and rewire as needed.
- Wiring can be done at any time of year, but you’ll want to pay extra attention from early spring to early autumn, as your plants will grow much more quickly. You’ll get faster results during this time period, but you’ll also want to give it time to heal at some point during the growing season. I still try to limit wiring to June and onward, giving it time to heal earlier in the year.
- While shaping your plants is ultimately stylistic and dependant on personal preference, you’ll find that existing techniques are better to fall back on. Some ways of styling are often incredibly stressful on plants and better saved for when you’re more familiar with basic techniques.