A shrubbery, shrub border or shrub garden is a part of a garden where shrubs, mostly flowering species, are thickly planted. The original shrubberies were mostly sections of large gardens, with one or more paths winding through it, a less-remembered aspect of the English landscape garden with very few original 18th-century examples surviving. As the fashion spread to smaller gardens, linear shrub borders covered up walls and fences, and were typically underplanted with smaller herbaceous flowering plants. By the late 20th century, shrubs, trees and smaller plants tend to be mixed together in the most visible parts of the garden, hopefully blending successfully. At the same time, shrubs, especially very large ones, have become part of the woodland garden, mixed in with trees, both native species and imported ornamental varieties.

The word is first recorded by the OED in a letter of 1748 by Henrietta Knight, Lady Luxborough to the fanatical gardener William Shenstone: "Nature has been so remarkably kind this last Autumn to adorn my Shrubbery with the flowers that usually blow at Whitsuntide". The shrubbery developed to display exciting new imported flowering species, initially mostly from the East Coast of British America, and quickly replaced the older formal "wilderness", with compartments of smaller trees surrounded by hedges, and little colour. It was a further part of the garden, beyond the terrace and flower garden that the house usually opened onto, and when mature provided shade on hot days, some shelter from a wind, and some privacy.

The shrubbery was at first the development of the plant collector wing of the growing movement of English gardeners, who in the early and mid-18th century eagerly awaited the new seeds and cuttings arriving at London nurserymen such as Thomas Fairchild (d. 1729) from America. There was some tension between them and the more landscape-oriented gardeners such as Capability Brown, though Brown's designs in fact allowed for flower gardens and shrubberies, which have very rarely survived as well as his landscape vistas in the parks.

Shrubbery is also the collective noun for shrubs in other contexts, sometimes used for shrubland, a type of natural landscape dominated by shrubs or bushes. The many distinct types of these include fynbos, maquis, shrub-steppe, shrub swamp and moorland.

According to the garden historian Mark Laird, "by the early 1750s, we may reasonably claim that the shrubbery had been invented". The exact appearance of the earliest examples needs careful reconstruction from such plans, letters, poems and visual images as have survived. A high proportion seem to have been viewed from "serpentine" paths, already a very fashionable layout for gardens, using an expanded version of the line of beauty promoted by William Hogarth's book The Analysis of Beauty of 1753. In plans some of these proceed in a single overall direction, with several more or less curves to left and right, and often no exit shown at the end. With large shrubs these would first bring plants into view when fairly close, supplying a succession of surprises. There was great emphasis on "graduation" in planting, with shorter plants, including herbaceous flowers, at the front near the path or lawn, with middle-sized ones behind, and the largest, and any trees, at the back. This principle, to some extent self-evident, has governed much planting ever since, for example that of Gertrude Jekyll, but was rather novel in European gardening at this point, where the different sizes of plants were usually planted in different areas.

A shrubbery was a feature of 19th-century gardens in the English manner, or the gardenesque style of the early part of the century. A shrubbery was a collection of hardy shrubs, quite distinct from a flower garden, which was also a cutting garden to supply flowers in the house. The shrubbery was arranged as a walk, ideally a winding one, that made a circuit that brought the walker back to the terrace of the house. Its paths were gravel, so that they dried quickly after a rain. A walk in the shrubbery offered a chance for a private conversation, and a winding walk among shrubs surrounding even quite a small lawn was a feature of the garden behind a well-furnished Regency suburban villa.

"Mr Rushworth," said Lady Bertram, "if I were you, I would have a very pretty shrubbery. One likes to get out into a shrubbery in fine weather." —Jane Austen, Mansfield Park (1814).

In the later part of the 19th century hardy Asian shrubs from the hills around the Himalayas and Western China became the most exciting new additions to the European garden, and large Asian rhododendrons now often dominate shrubberies and woodland gardens planted in the period that have not been carefully maintained, especially the invasive rhododendron ponticum. This had a wide range across Asia, extending to southern Spain, and it was introduced to England in the 1760s. But many sections of gardens, mostly from about 1890 to 1950, were planted as "rhododendron gardens" or "azealea gardens" from the start.