Stone can play a feature role in the garden, with different types of landscape stone available to complement every design style, from a woodland look to sleek, modern lines. Stone pathway options include crushed stone, peastone, and flagstone pavers. Stone walls may be constructed of slate, fieldstone or sandstone. Marble and granite can be used in wall construction as well as for obelisks, sculpture and other vertical focal points.
Pebbles and Crushed Stone
Pebbles are rounded stones the size of a marble or smaller, often called "peastone." Crushed stone is made up of irregular pieces of rock, which have been smashed in a crusher; these are usually sold by size, from stone dust that can be pressed into a flat surface with a roller, to 2- or 3-inch diameter rocks suitable for driveway surfaces for heavy equipment. Crushed stone is often a dull gray, but crushed marble or limestone in bright white are also available. Any of these small stone masses can be used as pathways, driveways or for the central "floor" of an outdoor room. Lay down weedcloth before pouring a several-inch-thick layer of small stone, and edge the area with strips or brick to keep the small stone from migrating into lawns or garden beds.
Fieldstone. Flagstone and Sandstone
Fieldstone--irregularly shaped and sized local stones of various geological types--can be used to create informal dry-stone walls or fitted and mortared to create estate walls such as those featured in the 2006 American Society of Landscape Architects' award-winning residential landscape designs. Large fieldstones can also stand in the garden as individual features or in groupings.
The Mississippi State University Office of Agricultural Communications suggests using flagstone--rough, but relatively flat, slabs of split rock--for paths and to define outdoor "rooms." Flagstones can be close-set, or left several inches apart and inter-planted with ground covers such as creeping thyme.
Sandstone comes in a wide variety of colors, and can be cut into neatly fitted blocks to complement traditional brownstone or brick architecture. An award-winning design featured by the ASLA included bluestone pathways; bluestone is a common type of bluish-gray sandstone which can be cut into flat geometric or irregular flags, like slate, but unlike slate provides sure traction even when wet.
Marble and Granite
Marble--a fine-grained, metamorphic rock available most commonly in white streaked with black, but also in shades of pink, green and black--can be cut into blocks for walls, but its propensity to take a high polish makes it a natural material for garden sculpture, fountains, obelisks or simpler vertical features like gateposts and birdbaths.
Granite is finer-textured than marble, and typically available in white and black or pink and black shades; although it does not polish as well as marble, it is put to similar uses, is less expensive, and better withstands harsh weathering.