Thirsty Tweeting Office Plants

We’re pretty good at maintaining our code base, not so much at maintaining our office plants. We use Arduino to keep our plants alive.
Thirsty Tweeting Office Plants


Here at Andium, we’re super excited to have finally moved into our new office space. We’ve been decking it out with walls covered in whiteboards, new shiny tech, and all the comforts of home. It especially started to feel like home when we placed a handful of these green leafy friends throughout the space!

Only we forgot to water them and within a week or so our leafy friends started to look like this…


We’re an IoT company, we’re better than this. How come our plants aren’t internet connected! Hopefully before it’s too late for this little guy I put together a solution using our anduinoWiFi shield and IFTTT. Time to give our plants a voice!

Getting Started

If you’ve got a green thumb you’ve probably already stopped reading, but if you’re like me and need to give your plants the ability to digitally beg for mercy and scream for some water then you’re in the right place.

To give your plants a voice you’ll need an Arduino Due, or Zero, an anduinoWiFi shield, (or any other WiFi connected Arduino that can speak to Adafruit IO) and lastly a ‘Capacitive Soil Moisture Sensor‘. Oh, and a glass of water. (Give it to your plant when we’re done, they’ll thank you via e-mail now).

Moisture Sensor

The soil moisture sensor is pretty cool, there aren’t many sensors where you’re actually encouraged to submerge in wet dirt, so enjoy that while you can. Not too much though, take note of this line..

Whatever you do, don’t submerge your sensor below that white line. Nothing above there will tolerate the moisture exposure too well, so be careful when watering your plants that contain this sensor.

If you clicked through to the next photo above, you might be wondering why I have the sensor submerged in a glass of water. Well, wonder no more!

How to Calibrate the ‘Capacitive Soil Moisture Sensor’

Our capacitive sensor has three wires which we’ll connect to 3.3v(red), ground(black), and (blue- signal) analog pin A1. When we calibrate our sensor we’re going to record the capacitance reading when the sensor is completely dry, and then take a second reading when the sensor is submerged (up to the white line!) in a glass of water. This gets us our extreme 0-100% relative humidity thresholds.

Wire up your sensor, run this sketch, and jot done your results. For reference, my dryVal was 807 and my wetVal was 415.

Once you have these two numbers you’re ready to configure the relative humidity mapping. Consider yourself calibrated!

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