Gsquared
Shohin
One thing to be aware of with boxwood, large cuts never heal over...NEVER. Small ones might, over time, truly callous and heal over completely, but large ones never do. At least from my experience and every boxwood bonsai I have ever seen, they all have scars. The good news is that the bark and exposed wood on box tend to be very close in color (look at your pic and you can see). The cuts look smoother than the bark, but overall the cuts are not nearly as noticeable as they are on some other species. So as you think on design, keep in mind that major scars are there forever. It may be different if you ground grow them, but box don't thicken up much from a couple of years in the ground. I had a few kingsville in the ground for 9 years and they went from pencil thickness to index finger thickness in that time. Not much for nearly a decade in a warm climate. Standard box grow faster. Still it takes decades to get a girthy trunk on a box. With all this in mind, I think Judy's suggestion of a broom style is more in keeping with this particular plant.
As far as pruning and root reduction, I have had no problems with doing both at the same time in the spring. Box have forgiving roots. The only boxwood I ever killed died because I didn't reduce the roots and repot it. Once you get this tree into a bonsai pot, be aware that the roots will overtake the volume of the pot fairly quickly. I would repot yearly or every other year. Otherwise the roots so fill the pot and getting water into the root mass becomes an issue.
As far as pruning and root reduction, I have had no problems with doing both at the same time in the spring. Box have forgiving roots. The only boxwood I ever killed died because I didn't reduce the roots and repot it. Once you get this tree into a bonsai pot, be aware that the roots will overtake the volume of the pot fairly quickly. I would repot yearly or every other year. Otherwise the roots so fill the pot and getting water into the root mass becomes an issue.
