We love using evergreen topiary and other shrubs in containers because they look great nearly year-round and are an excellent visual break from mixed container plantings (which we also love, of course). However, there can be the issue of bare soil at the top of the planter which always leads to the question–just top with mulch or dress with plants?
Annuals are an excellent solution as you can change them out to keep the planter looking seasonal, but if you want a one-stop solution, look no further than ground covers. They spread to cover the soil and then generally cascade over the edges providing a softening effect. And, they’re super easy to maintain.