Desert Rose Lateral Root Training December 2019

Lateral Root Training Update

I purchased this desert rose from the local Home Depot about six months ago. At first, I planned just to expose the caudex as I normally do with most of my adeniums; however, this one happened to look like a large potato. I'll leave it up to to figure out which one I'm talking about in the picture below. Not surprising for a desert rose from a big box supplier as the large growers are not able to curate the caudexes at mass scale.

I decided to give lateral root training a shot. I had seen so many pictures and videos online of the folks over in Thailand creating absolutely beautiful specimens. From what I can tell, most of them start off looking quite similar, and with the proper training, grow into intricate geometric roots.

I made a hard prune through the center of the caudex. Then carved a beveled edge as the surface for the new roots to grow. I coated the edge with rooting hormone and dusted the bottom with cinnamon, and hung it to dry for a few days in the garage. The trunk shriveled up a bit and felt soft when I when to pot it.

Desert Rose Lateral Root Training Wire Tie

I used a rectangular bonsai pot, which in hindsight was probably not the best idea. In the future, I will definitely be using a round pot to allow for even growth space around the caudex. I placed the plant on top of a circular plastic cutout to help prevent roots from growing on the bottom and then positioned it in the pot. I chose tropical bonsai soil consisting largely of lava rock as the soil media for the experiment. My thought was that the rocky coarse soil would force the plant to grow thicker roots. And yeah...I tied it down with speaker wire.

Progress

Here is the plant at the start of the unpotting. I had no idea what to expect, and was very surprised at how firmly the planted had rooted itself in the rectangular bonsai pot. 

Adenium in Rectangular Bonsai Pot
The roots wrapped around themselves to form a root ball in the exact shape of the pot in which the plant had lived for the last four months. With only a single data point, it is hard to draw a real conclusion, but the rocky soil seemed to allow for thick root growth. 
Desert Rose Root Ball
I used a pick and a small root rake in order to get the root ball out of the pot and to loosen the rocks out of the roots. You can see the desert rose performed as expected. Not a single root grew out of the bottom surface and the beveled edge was full new thick roots waiting to be pruned. Note that the bottom appears dark in color from the cinnamon used to cure the wound. The cinnamon flaked off while working on the plant to expose a healthy looking tan colored surface.
Desert Rose Bottom View Lateral Roots
I used bonsai scissors to clean up all of the small roots crowding the space between the large fat roots. I was selective in choosing which roots remained as it will shape the plant for years to come. In addition to pruning off roots right at the base, I removed all of the shooter roots that split off main roots in order to "lower" the root system. This will force the roots to develop at the bottom and thicken throughout. 
Pruning the Lateral Roots
In preparation for repotting, I positioned the plant on top of an upside down plastic cup and stretched the roots over the edge. I used landscaping tape to loosely secure the roots in the shape of the plastic cup. After a day of drying, this will be repotted with the upper portion of the roots exposed.
Tied Down Lateral Roots