A programmable sprinkler system ideally suited for use in an enclosure such as a nursery and/or arboretum includes a first overhead rail and a water pipe connected to a pressurized source of water. The water pipe is provided with a plurality of water valves placed at discreet intervals along its length and extend outwardly therefrom and is positioned alongside and close to the first overhead rail and parallel thereto. A source of electrical power is positioned close to and generally parallel with the first rail on the other side thereof and extends essentially its entire length. A plurality of second overhead rails have one end of each positioned near the valves and the first rail and extends outwardly therefrom, preferably at right angles thereto, defining a path along which the water is to be dispensed. A carrier mechanism rests on the first rail. Nested upon the carrier mechanism is a detachable car that includes a second coupling device to bring electrical power to it. The car also includes a plurality of water dispensing heads, a mating coupling for the valves on the water pipe, and a hose for carrying the water from the valve along the full length of the second rail in order to dispense water along the path provided by the second rail. Reflective devices together with a light source provide an electrical signal which controls the amount of water to be dispensed and the speed that the car and carrier are to move along the first and second rails, respectively. These signals are coupled to the programmable computer which is located in the detachable car.