Buxus sempervirens (common box) balls make excellent topiary plants and can be grown in containers/planters or in the ground, as individual examples or in conjunction with other plants.
Each box ball can be repeatedly trimmed to the same size and shape, or can be allowed to grow to a larger size by trimming the new growth to within about an inch of the previous trimming point each year or two.
Box balls can be grown in containers or in the ground. Plants in containers will need feeding, either with slow release fertilizer granules, ordinary granular fertilizer or liquid feed. Topiary balls grown in the ground will grow well with less care than buxus topiary in containers or planters.
A box topiary plant should be trimmed around mid-summer, and tidied up in late summer/autumn, or as required.