This project is on hold for now. The stuff in the GitHub repo hasn't been thoroughly tested and probably shouldn't be used as is. Feel free to email me if you have questions about the project.
The Hydro Mk I is an automatic watering system which monitors soil moisture levels. It can be used for up to two plants. At the moment, it shares one pump between the plants, but a second pump could be added easily.
The Hydro's code can be modified to work on just about any microcontroller, so long as it can be programmed with the Arduino IDE. All you need is 8K of flash (or more), 7 digital pins, and two ADC pins. The ATmega88 is perfectly suited to the project, mostly because of its ease of use and various interface choices.
GitHub repo for this project