A sprinkler system for lawns and landscaping is custom-fitted to each particular lot or area to be irrigated. Each in-ground, pop-up, rotating sprinkler head has a pattern defining plate fitted therein having a central opening made therein, as by laser cutting, solid particle deposition, or the like, the opening being congruent with the area to be watered, as adjusted for any sloped portions of the area. A pattern sampling aperture aligned with spray nozzles of the sprinkler rotates about the opening in the defining plate, feeding an amount of water to each radial line of the area about the sprinkler sufficient to reach from the sprinkler position out to the periphery. A speed control comprising a spring-biased cam and an opposing turbine wheel in the water flow slows spray head rotation at arc portions of longer water throw and speeds rotation where the throw is shorter, thus to obtain substantially uniform water coverage over all parts of the area served by each sprinkler head.