rock garden 
noun
1A mound or bank built of earth and stones, and planted with rock plants; a rockery.The tiny, tuft-forming Alpine poppy with flowers of white, yellow and zingy orange looks delightful in amongst the mat and cushion-forming plants of a rock garden....
- A few strategically placed stones and it would have made an excellent rock garden.
- Also known as meadow saffron, they look good naturalised in turf, in the rock garden, at the front of a border or under an apple tree.
1.1A garden in which rockeries are the chief feature.The park's gardens include a sunken garden, a rock garden, stream gardens and an Arboretum, containing many trees from the southern hemisphere....
- The remaining 12 acres provides enough room for a landscaped rock garden rediscovered during renovations and a broadleaf forest of beech, ash and oak.
- The 20 acres of grounds include a sun terrace, fruit garden and sunken rock garden, as well as a lakeside summer house and marina.