Orchard: An orchard is a piece of land specifically used for growing fruit trees. This is the most accurate term for a place where fruit trees are grown.
Garden: While a garden may have fruit trees, it is a broader term and typically refers to any piece of land used for growing plants, flowers, or vegetables, not specifically fruit trees.
Quay: A quay is a dock or a wharf, used for the loading and unloading of ships, and has no relation to growing trees or fruit.
Museum: A museum is a place where objects of historical, artistic, or scientific interest are displayed. It does not involve growing fruit trees.
Therefore, "Orchard" is the correct and most specific one-word substitute for a place where fruit trees are grown.