The GARDENA gardening expert
Only a few people manage this freehand, Ms. T., therefore, I would advise that you make a semi-circle template from sturdy carton in the desired ball size. This template should reach from the bottom pot edge or bottom of the bed to the “north pole” of the boxwood ball to be cut. While guiding the template around the boxwood, you will have the appropriate size for cutting the plant.
Usually, you begin shaping the boxwood with a much smaller plant than the desired ball diameter for later on. This way, the ball shape is achieved faster and the following year, it is already a small thick ball so that you only need to cut evenly. In the phase of making the ball larger, use two branch lengths per year: The first shaping follows the beginning / middle June plus subsequent light fertilising of the plant. It will then sprout new second shoots at the end of June. Shorten both sprouts by one fourth up to one third.
When the ball reaches the desired size over time, forego the second shoot which would mean a second cut and therefore, unnecessary work. Now, cut the ball once, the middle/end July – when no more second shoots are expected.
When shaping the ball, you must, time and again, cut new templates for the constantly changing size of the boxwood but with this method, you get a reliably even ball.