Electronic control units with one or two ways controlled by electrovalves for programmed watering of lawns, gardens, flower boxes and similar spaces, comprise a front panel (4) including a single push-button (6) for selecting a watering program, at least one push-button (10) for starting the selected program and a display (12). The control units further comprise an electronic micro controller (13) which in response to the operation of said push-button (6) for selecting a watering program causes the visualization of the duration, the frequency and, preferably, a number indicative of the selected program, and in response to a single operation of the start push-button (10) causes the immediate start of the selected watering program and the visualization of the time to the end of watering, while in case of operation of the start push-button (10) for a variable number of times programs the delayed start of the selected program and the visualization of the time to the start of the watering program. If the control unit is of the two-ways type, the front panel (4) comprises two start push-buttons (10A, 10B) used for associating a selected program with one or another of two electrovalves (14A, 14B) for controlling the two ways (5A, 5B) and for the immediate or delayed start of said selected program.