To do this right, preparing for a thick trunk with powerful buttressing roots must begin right away...
Planting in relatively shallow (~4" tall) pots provides ample space for growth and encourages roots to extend outward.
8" clay bulb pans
To further encourage outward growth/extension of roots, a ~2" layer of pea gravel in the bottom of the pots is formed into a raised mound, which is covered by the round black piece of heavy duty plastic sheeting you see in the photo.
Plastic sheeting will prevent the downward extension of roots at/near the center of the rootball.
In other words, the roots will be forced to extend outward.
Next, the soil mix is prepared.
It consists of 6 parts
'cactus mix' to 2 parts
perlite to 1 part
And don't forget about the pea gravel which was placed in the bottom of the pot---this will help to enhance drainage.
Next step is to add soil mix around the base of the mound.
Note that I've purposely left the very center part of the plastic sheeting visible in the photo so you can more readily see the depth of the soil mix. Only a thin layer of soil mix was then added on top of this plastic sheeting prior to placing plants in the pots.
Starting with young plants is a must...
in 6" pots; purchased at Lowes
Here are the plants; individually separated from the first pot.
A closer inspection of the rootball on our tallest plant...
The same rootball is shown here immediately after pruning off the tap root...
Here is what our initial planting looks like...
A closer look at the base of this plant reveals petioles (leaf stems) positioned at relatively close internodes...
It is my hope that this will lend itself toward the emergence of multiple growth points when it comes time to perform the first major pruning (trunk reduction). This is vital for the encouragement of a thick trunk and strong lower branching.
Here ^^^ you see the 3 plantings I was able to prepare with the 3 pots I had. I plan on preparing 3 additional plantings as soon as I am able to obtain 3 more pots (the ones I got my hands on were the last ones the store had).