Adafruit Chirp! The Plant Watering Alarm [ADA1965]
Let's be honest - the hardest part about owning a houseplant is not killing it. And the hardest part about not killing your houseplant, at least for us, is remembering to water it. The Chirp! Plant Watering Alarm is a new device from wemakethings that helps extend the life of your plant by reminding you to water it.
It's really simple to use. You just stick the inconspicuous black PCB into your plant's soil with a CR2032 battery in it, click the button on the back to set the "dry point," then water your precious houseplant. The device then senses the moisture in your soil and "chirps" through a piezo whenever your plant reaches that dry point again - reminding you that your plant is thirsty!
This product does not come with a CR2032 battery but you can pick one up here!
That's just the basic function of the device. It's also completely hackable and customizable - connect to it over I2C to interact with your Chirp! and log light and moisture data for ultimate houseplant control. Or be creative and come up with a bunch of cool plant hacks.
For more info on how the Chirp! works, check out their informative website. The moisture sensor is also entirely open source and all the code and schematics are available here.