How to control irrigation? This is what I have been asked so many times. For me the answer is pretty simple. I do not trust weather forecast based irrigation control since rain amount can be extremely different from one to the other location especially in summer times with thunderstorms and other localized rain events. Therefore I recommend a couple of soil moisture sensors placed on site. But what kind and brand of soil moisture sensor to choose? There are so many sensors out there that is hard to decide which is the best one for your application. For price sensitive applications I now go with the TRUEBNER SMT50 after mixed experience with the Vegetronix VH400. I recently found a comparison between the SMT50 and the VH400 which shed light on the detailed technical differences between these sensors, see here.