Use a Moisture Sensor with Arduino

This sensor allows you to read the moister in soil

Written By: Madeleine Schappi

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Very Easy
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For the absent-minded green thumbs, you'll need to use one of these moisture sensors!

In this guide, you will learn how you can use a moisture sensor with an Arduino, to determine the amount of moisture in a substance.

After completing this guide, you could create an Arduino plant watering system or a simple moisture detector for your beloved garden plants.

Step 1   Get your moisture sensor and probe

  • You will find a moisture sensor probe and breakout module

Step 2   Connect the Probe to the Breakout Module

  • Connect the Probe to the Breakout Module.
  • The order of the wires doesn't matter.

Step 3   Connect the 5V line from the Arduino to the Module

  • Connect the 5V line from the Arduino to the Module.

Step 4   Connect the Ground line from the Arduino to the Module

  • Connect the Ground line from the Arduino to the Module.

Step 5   Connect Analogue 0 to the Module

  • Connect Arduino Analogue 0 to the Module.

Step 6   Upload the code

int ledPin = 13; // Wet Indicator at Digital Pin D13
int sensor = 0; // Soil Sensor input at Analog Pin A0
int value = 0;

void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.println("SOIL MOISTURE SENSOR");

void loop() {
  value = analogRead(sensor);
  value = value / 10;
  if (value < 50) {
    digitalWrite(ledPin, HIGH);
  } else {
    digitalWrite(ledPin, LOW);
  • Copy this code and load it into the Arduino IDE and Upload it
  • Open the Serial Monitor
  • Out of moist soil you should get a reading around 100
  • Once in moist soil or a glass of water you should get <40

Step 7   Make sure your Christmas Tree doesn't dry out

  • Each year our Christmas Tree dries out and turns brown long before Christmas Day. This year, using the moisture sensor, we are going to make sure it alway has enough water! 
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