Smother weeds with ground-hugging phlox. Delicate in appearance but tough in character, these spreading perennials soften the edges of paths and grow in dry rockeries and on sunny banks and slopes.

Left unpruned, it can become straggly and bare at the base. Even with regular trimming, it is often best to replace rosemary every five years or so with a new young plant, and luckily it’s very easy ...