I have 2 boxwood standards having a single ball at the top. When purchased in spring 2012, the bottom of the ball was comprised of branches radiating outward from the trunk at an angle. While the shape has improved, how can a ball be created without seeing the many branches? Is it merely a matter of time, or, can something be done to expedite the desired shape?
If I understand your question correctly, you are asking if you will ever create a perfectly round ball on the top of the trunk. Without seeing your plants themselves, the short answer is: probably not. Some branches may be visible at the bottom of a topiary ball, even in the best specimens. This will be especially true if the tree is grown in a shady situation – the additional shade cast by the ball itself may discourage foliage growth on the underside of the ball.
The long answer is that, over time, you might continue to see improvement in the shape. Careful clipping of your topiary twice a season (in early May and mid-August) will help keep the ball compact, and you can selectively snip to help cover your branches.
Topiary is both an art and a science, though. If you are interested in pursuing it, you might check the Toronto Botanical Garden’s Weston Family Library for how-to books. The public is free to use the library, and members of the TBG can even check books out.
Alternatively, you could visit the Toronto Public Library for books such as Container Topiary by Susan Berry.