Heres a circuit I built for monitoring soil moisture. Its simple to build and lights an LED when the soil becomes dry and its fully adjustable to individual standards. I was able to build mine and place the entire circuit inside of a pin and I am using it in my living room on my San Pedro cactus. THis circuit has a lot of potential because of its small current draw and could easily be modified to water plants outside automatically when soil becomes dry. No more packing in water or worrying about out door plants. Any thoughts?