Susquehanna Bonsai Club

The premiere bonsai club of south-central Pennsylvania


Mauro Stemberger – Susquehanna Bonsai Club

Sorry for the VERY LONG absence of updating this site. My time with 2 jobs, a family and everything else made time hard to come by. Going forward I promise to update this site regularly as I now have time to do so 🙂

Mauro Stemberger : Susquehanna Bonsai Club –  Club members bonsai critique -November 2017

Sheila opened the meeting with congratulations to Jim Kopenhaver who was elected president of SBC for next year. She welcomed Mauro Stemberger back to SBC and gave us an update on Mauro’s activities for the year. Mauro is now sporting a wedding ring and has essentially completed a bonsai book which will be available in the spring.

Mauro began his tree evaluation with his usual grace and visual acuity. The first tree presented was a Limber Pine (Pinus flexilis). Limber pines have short needles and bud back easily. Mauro is not a fan of the windswept style. He suggested looking for the front and developing the style, remove the bark from the existing gin. Mauro saw a smaller tree by creating separate jinn without a shari with the straight branch and then developing an apex by that jinn. Use the more compact part of the tree to develop the branches of the tree. The branches can be reduced slowly. In spring pinch the candles, letting the buds grow until July and then cut shoots by ¾, buds will form at the base of the cut candle. Wait until the candles harden off and cut off the old candle in the spring.

Privet (Ligustrum sp.) is a strong grower. Mauro suggested building taper to the trunk with 4 to 6 diameter changes since this is a strong tree and a fast grower. The root ball can be reduced, but first finish the tree and then put it into a bonsai pot. After the spring shoots are hardened, you can defoliate the tree and shape it and it will grow again. Build the branches and reduce the length and work on the shape. In the spring, work on the inner lines, wire and create structure of pads and start to shorten the tree. After the tree is developed and in a bonsai pot, control growth and size of leaves by slightly stressing the tree with less water. Food, light and water quantities control growth. We do not want to have a branch take off and destroy the form of the tree. Deciduous trees’ root ball can be cut hard when potting the tree. Conifers’ root ball cannot be cut back drastically when re-potting.

Yew (Taxus baccata): The tree was collected from a tree nursery and was growing in clay soil. The root ball was cleared of the clay soil and planted in “bonsai soil”. Mauro said that this was a fine procedure for a yew since it does not require mycorrhizal fungi in order to grow as pines do. It would be better to be planted in a soil that does not have any organic material in it since the organic material will hold water. The tree needs a good draining and airy soil when the branches are wired and pinched and growth is controlled. Akadama, pumice, and lava in 2-1-1 ratio would be an example of an appropriate soil. It has a good root ball. Next decide where the front is, bring the tree a little forward to increase the concept of three dimensions. Next, start up the trunk and select first, second and back branches. The lower back branch could be moved forward to become a welcome branch. Remove the chicken feet roots and decide which of the two uprights will become the apex. The other top branch could be a back branch or possible a jinn. When we start shaping, we want the tree’s energy to go to the branches rather than to the apex.

Pitch Pine (Pinus rigida): Treat like a black pine. Change the angle of the tree, it can reach this angle. This will bring some roots above the soil line. The exposed roots will need to be potted as the nebari is adjusted to soil level. Hide the bend in the back and bring the branches forward. Push the bottom branch down and shorten some of the lines. Subdivide the pads to develop them. Move the rhythm up the tree, from heavy strength of the bottom to lighter on the top. Reshape the back dead branch to a hollow or create a jinn. Bend branches in the cooler weather. Use raffia for large bends and guy wires to bring the branches down and ever few weeks, tighten the wires. Don’t allow the tree to freeze, if you are making adjustments during the winter months rather keep the tree in a cool greenhouse. Avoid the hottest months of the year to do heavy bending.

Boxwood (Buxus sempervirens): Slowly open up the branches which are now too close. If the tree has room it will fill the space. Develop back branches to create depth. Prune harder on top to develop branches. If the pads are nice, allow it to grow a couple of inches and then prune and continue to clip and grow.

Rocky Mountain Juniper (Juniperus scopulorum): Check what is under the soil for the nebari – where is the original root ball? First build your plan – what is your design, and then take away everything that is not necessary, then clean and wire the entire tree. Junipers respond to being wired, twisted and breaking the fiber of the wood, it will recover more quickly than if the fibers are not stressed. That is the first step of your journey with the tree, there may be more than one option that is pursued during the journey with the tree. Junipers require as much sunlight as they can get. Grow in full sun to get strong compact trees. Yews, on the other hand, are an under-story tree and grow well with reflected light. If the tree is not used to growing in direct sunlight, slowly move it into more intense light to prevent the leaves from burning.

Yew (Taxus sp.): This specimen was grown in the ground and collected then fed heavily. The top was killed off and a jinn formed. Reduce the jinn since it is overpowering the tree. Build the proportions for the tree. Possibly open up a shari to define the edges of the live vein. Possibly change the orientation and have the right branch be the apex. We do not have to limit our imagination to the angle the tree was potted. Use all the information you can get from the tree, sometimes the hidden idea is the better one. An exception to this is Mugho Pine which will grow more strongly if it does not have to reorient itself.

To see more of Mauro’s handiwork or to reserve his book, go to his website at

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Dinner and demo with Mauro Stemberger – Susquehanna Bonsai Club

Mauro Stemberger. Italian stallion and bonsai extraordinaire! Mauro’s demo on a Rocky Mountain Juniper for the club.

Following is from the club newsletter editor Ross Adams:

Mauro works as an architect and as a bonsai artist.  He became fascinated with the art of bonsai when he was fourteen and joined the local bonsai club in Feltre, Italy.  During his formative early years he was able to take workshops with, among others, Hotsumi Terakawa, Marc Noelander, Horst Crekler and Edoardo Rossi.  Meeting Alfiero Suardi and Enrico Savini inspired him to take his techniques to a new level.  In 2005 he founded the Italian Bonsai Dream Workshop with a group of enthusiastic bonsai folk so they could become totally immersed in the work and enjoyment of bonsai.  Go to Facebook or his website for more information.   
As Mauro worked on the Rocky Mountain Juniper demonstration tree, he shared the following.    The best time to work on Rocky Mountain Juniper is when it starts to point (tips of branches are elongating).  Mauro decided
to create a double trunk Bunjin style bonsai with the second apex low on the tree.   
When styling, first get rid of the parts that are not going to be used.  Also eliminate straight, horizontal and vertical lines.  Geometry, lines and spaces are of utmost importance in bonsai. If there are any decaying deadwood areas on the trunk, remove the spongy deadwood and treat the remainder with PC Wood Hardener.  If the tree is strong you can safely remove up to 70% of the foliage.       
Before any significant cutting of branches, however, It is important to find the live veins.  If you cut branches that are important to a live vein, l the live vein may die.  Equally important is to make a clean line between the dead and live veins.  Mauro uses a Swiss leather makers tool to do this (It resembles a scalpel).  He also uses a tool made from a chain saw blade bent into a u-shape (Scorp) to clean off the bark from he dead vein areas.    
For severe bends, use raffia.  Putting tape on top of the raffia will maintain moisture on the bend and the branch will recover more quickly.  Wiring is the language of
Bonsai.  Test the branch before you wire it to determine the size of wire needed.  Mauro prefers copper wire since it is stronger and you can use a smaller gage.  Start with larger wire on the base of the trunk and the basic structure of the tree, then wire the secondary branches with appropriate wire and finally the smallest branches with fine wire.  Keep the wire flow continuous and in contact with the branches to distribute stress to the trunk of the tree.  Wire so that the wire will become tighter after the branch is bent.     
Mauro loves to collect trees and to do the first designs of trees.  Unlike bonsai professionals in Japan who are specialized, Mauro does all stages of development and maintenance of trees.  
In Europe the collecting is done in February to the end of April at lower altitudes.  Mugo Pines and higher altitude trees are collected from May to June.  While collecting it is important to determine where the live 
veins are and if you can successfully collect roots associated with the live veins. Equally important is the trunk movement.  When you collect trees, mist and adjust the temperature up or down so that the tree continues to suck water.   
Olives are easy to collect since the base can be cut off horizontally and the tree will root easily.  Oaks in Italy grow in clay soil and after collecting, plant them in perlite and put a black plastic bag over them and keep completely dark in winter then change to a transparent bag when it starts to push in the greenhouse, then to  air in the greenhouse and then outside.  If yamadori trees are strong, you can style them after having been grown in a pot for three years.

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Thanks for reading 🙂