A pair of box plants, meticulously clipped, makes a garden in itself, placed at the top of a flight of steps, or beside a house door. Box is never out of season, is evergreen, mercifully slow-growing, and perfectly hardy, smiling at frost or rain. It even has a faint scent when the small greenish-yellowcome out in late spring. It can be planted as the centre-piece of a large pot of mixed plants, but looks much better on its own, and other pot plants can be strategically arranged nearby, such as tulips in spring and fuchsias for summer.
Box is a British native which has been grown in gardens for centuries for edgings and topiary; indeed, Pliny the Younger had a topiary garden at his Tuscan villa nearly two thousand years ago, with his name and that of his gardener cut out in box, and there is no reason why box in a pot need be a plain ball or pyramid. You could try your hand at a peacock or dove.
In the open, box will grow into a tree, the wood being very hard and precious, but in a pot it can be kept to any size you want. There are variegated forms with green and gold or silver, but in my view neither surpasses the plain green.