Ornamental gardens are gardens which are designed for the purpose of aesthetic pleasure, rather than the production of crops. Landscaping plans often integrate ornamental gardens into their designs, and many cities have civic ornamental gardens for the pleasure of residents. Some botanical gardens also include ornamental sections which showcase striking and interesting ornamental plants, as opposed to preserving botanical specimens, which is the primary purpose of a botanical garden.

The practice of laying out ornamental gardens appears to be ancient. Humans have long had a fondness for art and beautiful things, and once the basics of agriculture had been mastered, ornamental gardens were not far behind. In fact, ornamental gardens were even included in the Seven Wonders of the Ancient World, in the form of the Hanging Gardens of Babylon. These gardens were allegedly designed as pleasure gardens for a ruler's wife.

Ornamental gardens often surround public buildings to make these buildings more visually interesting. Churches, galleries, and other buildings devoted to contemplation are also commonly surrounded with ornamental gardens which are used by their members. Some religions even expressly include devotional activities which are meant to be performed in a garden. Other ornamental gardens are used to decorate private homes.

The layout of ornamental gardens can be incredibly varied, depending on the climate, the plants involved, and the nature of the surrounding architecture. The ornamental gardens at locations like Versailles, for example, are extremely formal and elegant, with a complex layout of beds and paths which is often best viewed from a distance. By contrast, the ornamental garden which surrounds a small cottage may be done in a more casual style.

In addition to being pleasant to look at, ornamental gardens are also pleasant to use. Many ornamental gardens include recreation areas for playing sports, walking, or simply sitting and enjoying the garden, and some have space for performances of music and theater. Events like weddings and cocktail parties may also be staged in an ornamental garden, with the surroundings of the garden contributing to the decorations at the event.

While ornamental gardens are sometimes dismissed as frivolities with no practical applications, they do actually serve a function beyond looking pretty. Plants can help to regulate temperature, keeping a climate more temperate and comfortable while acting as air scrubbers, removing pollution and keeping the air fresh and clean. An ornamental garden can also provide habitat for birds, butterflies, and other creatures.