I’d be interested in doing this too – I am setting up a greenhouse for deciduous tree cuttings with bottom hot water heat and am interested in using a ‘leaf’ as a humidity sensor to control a misting system. I might also be able to control the system through another commercial product that is controlling other aspects of the greenhouse but would much better do it through Opensprinkler as it is much more flexible.
I am using OpenSprinkler for controlling my container yard water and will probably start using it to automate my 10 propagation houses watering as well. Would love to be able to control zones individually as per input from soil moisture sensors like http://www.decagon.com/en/soils/volumetric-water-content-sensors/.