In strict terms, a formal garden is one that is entirely symmetrical, with one side mirrored by the other in a highly planned geometric pattern. Although there are many gardens of which this is true, formal gardens have now also come to signify a design that is laid out with a degree of geometry and regularity, and with stylised planting - not necessarily with mirror images.

From the simplicity of a lawn punctuated by a single island bed to the complexity of an intricate knot garden, many types of formal garden may be planned. However simple they may be, formal designs are typically ordered and elegant, well proportioned and balanced, and often strongly symmetrical or patterned.

Features typically include straight paths, closely mown lawns, borders defined by low hedges or edging plants, neatly clipped hedges or topiary, framed vistas and focal points, formal bedding in blocks of strong colour, and, on occasion, knot gardens and parterres.

Formal gardens require very regular and precise maintenance and are usually very labour-intensive. The more regular the design, the more any slight flaws will stand out.