There can be no gardens in this world, or in any Otherworld, unless there is something beyond their boundaries which is not a garden. Gardens are enclosures; they are shaped to express a meaning, a vision of the ideal world, a dream of escape or seclusion. In fantasy, they may be physically distinct from the surrounding world, or magically distinct, as Polders are; they may be unreachable from the surrounding world (> Secret Garden), or reachable only if those who search for them trace a Labyrinth into their heart; they may transform those who enter them (> Into the Woods); they may constitute a Portal into an otherworld.
At one time it was thought UK fantasy homed in on the garden while US fantasy moved outwards into the wilderness or the world. There is an element of historical truth in the thought; but English-language fantasy writers, on both sides of the Atlantic, have tended to become less easily distinguishable in the years since J R R Tolkien.
In Biblical typology, the garden (which represents Eden) stands at the opposite pole to the City (which is Jerusalem); but does so as part of a complex theological drama in which the first becomes last, Eden becomes Jerusalem, time past becomes time future. An Underlier resonance of this drama can be assumed to operate, however obscurely, whenever gardens are highlighted in the literatures of the West. [JC]