Indoor gardening is a great way to use some extra window space to produce either an aesthetic boost to your room or some herbs to be used in food and cooking. Unfortunately, every plant owner will forget to water at some point, which can result in the death of the poor plant.
But, what if the plant could water itself? Coming soon to a microcontroller near you: the self-watering plant!
I have set up a basic circuit on a breadboard, and everything seems to be running smoothly. An Arduino Nano is currently running a short sketch, which periodically tests soil moisture and records the results on an OLED for display to the user, along with the maximum and minimum moisture values detected since the device's last reset.
The OLED also displays the moisture warning level, the maximum moisture reading allowable before the device will alert the user to water the plant (currently using a pair of red/green LEDs, but in the future I would like to use a tricolor LED strip wrapped around the planter). Currently, this setting is manually inputted by the user with a potentiometer, but I would like to design a smoother user interface. Perhaps in the future, I may setup a system providing preset warning levels based upon the input of soil type and plant water usage.
As of now, I am using a cheap YL-38 moisture sensor bought off of ebay, however in a previous prototype of this project I had continuous power running through my moisture probe (the probe that came with the sensor) rather than only running the sensor board when I needed a reading, which resulted in serious corrosion of the probe over the course of a month or two. Now, the board is powered over digital briefly, only when taking a reading. In the interest of saving some cash, I have created a new, albeit less precise, probe using cardboard to maintain a constant spacing between the two wire probes.
I've been growing plants on the windowsill of my dorm room for most of this year, and the results have been fantastic. Lush green foliage now brightens up my room, and I have herbs to use in eating and cooking.
I try to be a responsible plant owner, but sometimes I just can't be there to water my plants. In addition, it's nice to know how moist the plant's soil is when I can be there to water. Herein lies my inspiration for this project!