Just FYI, I made Zigbee Environment Sensor which is expandable. For more detail, please follow the link. I do not want to bother everyone with detail here. One of the expansion is capability to read Analog Input.
You can get a capacitive soil sensor like below.
There are 3 wires to connect for power, ground and analog voltage.
You will be able to use and monitor your soil like here.
If you are interested on setting one up and need more detail, feel free to PM me.
Thanks
Iman
