"W" wrote:

We planted a Calandrinia Spectabilis in a small succulent garden. This
thing grows like a weed. It has quadrupled its size in four months and
looks set to take over the entire garden. I would like to transplant this
from the garden into a planter, then trim the excess off as it hangs over
the planter.

Are there any tricks for successfully transplanting this plant?

How deep does the soil need to be? I was thinking of transplating into a
concrete bowl that is 21 inch diameter and 8 inch depth in the middle.

Would help to know your growing zone, and if you'd post a picture.
There is no reason it can't do well potted, just be sure your concrete
planter has good drainage.