If we could give one piece of advice to someone starting a dry garden, it would be this: cover the soil.
Why it works
Bare soil bakes in summer and loses water fast. A layer of mulch keeps it cooler, slows evaporation and feeds the soil as it breaks down.
What we use
Fallen leaves from the street trees, which the neighbours are happy to give away, and wood chips from a tree-felling company. Both are free.
How thick?
About 7 to 10 cm, kept a hand's width away from stems so they do not rot.