Inspired by some of the most amazing stories of Maples in Japan, I’ve tried my hand at developing more than a few deciduous trees from scratch over the last ten years. What do I have to show for it? Some success; some utter failure; and some modest progress. The value of the failures is possibly greater than the value of the successes, if only because they have taught me many of the mistakes to avoid in developing these kind of trees. 
Starting about 7 years ago I have made some progress on a few of the trident maples in my original batch of seedlings. Meanwhile, I started a second batch of tridents last year; this time with the intention of growing many more of them to maturity than the first time around. The trees in the first batch are coming along, each at their own pace. Here’s one example:
June 2013, after a partial defoliation and wiring. The sacrifice branch has been established at the back.
January 2015, after one year planted in my yard. The trunk more than tripled in diameter.
Late April 2015, I defoliated the finished branching and left the sacrifice to continue growing.
January 2016, Dug up and potted into a bonsai container. I cut the top of the sacrifice but did not remove the entire thing. The wood growth swelled right over the wedge that I had cut in the spring.
While this tree still has a long way to go to be a great bonsai, I’m optimistic that the compact node and branch structure I’ve been able to put at the core of the tree will serve it well in the next few years. The tree needs to grow a new sacrifice from above the original one to help smooth out the taper. My goal for the tree is to continue the trunk refinement while I simultaneously work on the branching.
The other element that needs to be addressed is the root base. For a trident the tree is nothing special. I potted it a bit high in the container with the thought that I may try a ground-layer to get a new start on small roots at the base.
The story of my second batch of seedlings fills in what happened with the tree above before the first photo I have in my archives from 2013. This is my second batch of trident seedlings:
In November 2014 I picked a couple hands full of trident seeds off a street tree near my house. After de-winging them I put them in a jar for soaking; I followed that with leaving them in the fridge over the winter.
February 2015, planted out in a flat they starting to sprout. The germination rate was good and I ended up with about 50 seedlings.
May 2015 – By the end of May they were already large enough to wire. I wanted to be able to put strong movement into most of these trees so I started with the outer seedlings in the flat and wired each one while it was still in place. The wire was removed about a month later, after the trunks set.
April 2016 – the seedlings are a bit over a year old and I’ve transplanted them into individual containers. The growth since last summers wiring has been twisted up a bit using a new batch of wire.
With these seedlings I’ve taken a lot of time to create movement in the trunks before they get too big to work with. It doesn’t take much wood in a trident to make it stiff enough that you can’t get any bend into it. I recommend using wire at every opportunity to add movement to future trunk sections and to adjust branching as needed.
Incremental progress is the magic of bonsai, because really there is no magic. It’s just a logical set of steps, each one executed at the right time, and with the intention of improving the tree or trees over a long period of time. Whether you start with a piece of nursery stock that needs cutback and branch development or a jar full of seeds, the process you use will be what makes your trees mature into great bonsai.