It is mid winter at Shibui Bonsai. July and August are the months I usually dig all the stock from the grow beds and assess them.
This year I have started on the trident maples.
In the past I have left trees in place for up to 5 years. They certainly grow large but the resulting roots are huge which makes them very difficult to dig up and does not make the best nebari. Now I prefer to dig every winter. Not only is digging much quicker and easier because I can cut through the smaller roots with the shovel, but the more regular root pruning promotes a much more ramified root system leading to much better nebari. Growth of the trees will be a little slower overall but the increased quality is worth the small growth rate sacrifice. the trees shown in this post have been in the grow beds for just one year.
Each tree is dug and the soil shaken off the roots.
trident as dug
I then shorten the roots and make any adjustments that might be needed. You’ll see that these trees already have a well defined spreading root system.
Roots pruned
That gives me a planting angle and from that I can prune the top of the tree to give the best trunk lines and taper.
top pruned
I then heel the trees in a communal group to await assessment. They can sit like this for several months, right up to bud burst if necessary, without any problems.
tridents ‘heeled in’
Those that show immediate potential as small bonsai will go into pots and end up in the 2016 Shibui Bonsai catalogue. Others will be replanted in the grow bed to increase in size for another year.
There are many ways to develop really good nebari on trident maples. Before planting new seedlings in the beds I cut the roots really short, leaving only well placed lateral roots that will hopefully form the basis of a well placed radiating nebari
First root pruning. Just leave laterals
This tree was developed using root pruning alone.
As dug
After pruning
Even better results come from growing the seedlings through a hole drilled in sheet metal.
Underneath you can see the metal plate.
When the roots are pruned and the plate removed the roots are perfectly flat. That’s going to make fitting it into a shallow bonsai pot so easy.
flat base after removing the plate.
This post shows more details of this technique Create show stopping nebari
Promoting lateral root growth and discouraging vertical growth not only form great nebari. As the tree relies more and more on the lateral roots the base of the trunk widens to form a thicker, buttressed base and adds taper to the tree.