ESP32 - Automatic Irrigation System

This tutorial instructs you how to make an automatic irrigation system for the garden using ESP32, a soil moisture sensor, relay, and pump. In detail:

Hardware Used In This Tutorial

1×ESP-WROOM-32 Dev Module
1×USB Cable Type-C
1×Capacitive Soil Moisture Sensor
1×12V Pump
1×Vinyl Tube
1×12V Power Adapter
1×(Optional) DC Power Jack
1×Jumper Wires
1×(Recommended) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kit:

1×DIYables Sensor Kit 30 types, 69 units
Disclosure: some of these links are affiliate links. We may earn a commission on your purchase at no extra cost to you. We appreciate it.

Buy Note: Numerous capacitive soil moisture sensors available in the market are of poor quality, regardless of the version. We strongly advise purchasing the sensor from the DIYables brand via the link above; we conducted tests, and it performed reliably.

Introduction to Soil Moisture Sensor and Pump

We have specific tutorials about soil moisture sensor and pump. Each tutorial contains detailed information and step-by-step instructions about hardware pinout, working principle, wiring connection to ESP32, ESP32 code... Learn more about them at the following links:

Wiring Diagram

ESP32 Irrigation System Wiring Diagram

This image is created using Fritzing. Click to enlarge image

If you're unfamiliar with how to supply power to the ESP32 and other components, you can find guidance in the following tutorial: How to Power ESP32.

ESP32 Code

/* * This ESP32 code is created by * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit */ #define RELAY_PIN 17 // ESP32 pin GPIO17 that connects to relay #define MOISTURE_PIN 36 // ESP32 pin GPIO36 (ADC0) that connects to AOUT pin of moisture sensor #define THRESHOLD 2800 // CHANGE YOUR THRESHOLD HERE void setup() { Serial.begin(9600); pinMode(RELAY_PIN, OUTPUT); } void loop() { int value = analogRead(MOISTURE_PIN); // read the analog value from sensor if (value > THRESHOLD) { Serial.print("The soil is DRY => turn pump ON"); digitalWrite(RELAY_PIN, HIGH); } else { Serial.print("The soil is WET => turn pump OFF"); digitalWrite(RELAY_PIN, LOW); } Serial.print(" ("); Serial.print(value); Serial.println(")"); delay(200); }

Quick Instructions

  • Do calibration to determine the wet-dry THRESHOLD, see ESP32 - Calibrates Soil Moisture Sensor
  • Update the calibrated THRESHOLD value in the code
  • Open Serial Monitor on Arduino IDE
  • Upload the code to ESP32 board
  • See the result on Serial Monitor. It looks like the below:
The soil is DRY => turn pump ON The soil is DRY => turn pump ON (321) The soil is DRY => turn pump ON (541) The soil is DRY => turn pump ON (745) The soil is DRY => turn pump ON (864) The soil is WET => turn pump OFF (1265) The soil is WET => turn pump OFF (2011) The soil is WET => turn pump OFF (2365) The soil is WET => turn pump OFF (3375) The soil is WET => turn pump OFF (3679)
Autoscroll Show timestamp
Clear output
9600 baud  

Code Explanation

Read the line-by-line explanation in the comment lines of the source code!

Video Tutorial

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