Homemade Soil Humidity Sensor

Sensor reading when dry

Sensor reading when wet

The alert system functions by illuminating the green LED while the plant is properly watered and switches the red LED on when the plant is in need of watering (or dry). Also, when the soil is dry and the plant is watered, the system will turn the red LED off and the green LED on.

A small improvement to this system would be to have the green LED dim proportionally as the soil becomes more and more dry, then the red LED would ultimately turn on when the soil is completely dry.

A couple long-term improvements would be to (1) devise an automated watering system or (2) have the plant twitter or sms the owner’s phone to remind him/her that it needs to be watered.