Automatic Watering System for Plants using Arduino

Lets make an automatic watering system. This project is an extension of our prior experiment, where you learned how to connect moisture sensor to Arduino. This time we are also going to connect a relay and water motor to the Arduino. We will then write a program to take input from soil moisture sensor and switch on or switch off the water motor based on the data received from soil moisture sensor.

What will I learn from this video and post?
  1. Connect Soil Moisture Sensor, Relay and water motor to Arduino Uno.
  2. Write a program to accept input from soil moisture sensor and switch on or switch off water motor.
  3. Explain the source code.

What is Automatic Watering System for plants?

The automatic watering system helps you to water plants at your home, garden or farm in your absence. It uses technology to detect the moisture level of the soil and automatically water the plant when there is no moisture detected in the soil.

Can I make one myself?

Yes, this is what learn by watch do, helps you to learn to do things yourself. We have created a video and this post to show you the procedure to make it on your own. If you will follow both carefully you will be able to make it yourself. If you face any problem as in the comment. You can also ask us for the paid services.

How long does it take to make an automatic watering system myself?

It depends on your prior knowledge and experience with Arduino. If you are new to that and follow the video and instructions given in this post, you should be able to make it within a day. But if you are planning to showcase in some science exhibition, We recommend you to start at least one week prior to the deadline.

What are the required components?

The required components are given below. We have also provided links to buy the components from Amazon and Flipkart so you do not have to waste your time in search for the right component.

  1. Arduino Uno R3: |
  2. Soil moisture sensor: |
  3. Buzzer:
  4. 4 Channel Relay for Arduino: |
  5. Jumper wires: |

Source code

int ACWATERPUMP = 13; //You can remove this line, it has no use in the program.
int sensor = 8; //You can remove this line, it has no use in the program.
int val; //This variable stores the value received from Soil moisture sensor.
void setup() {
  pinMode(13,OUTPUT); //Set pin 13 as OUTPUT pin, to send signal to relay
  pinMode(8,INPUT); //Set pin 8 as input pin, to receive data from Soil moisture sensor.

void loop() { 
  val = digitalRead(8);  //Read data from soil moisture sensor  
  if(val == LOW) 
  digitalWrite(13,LOW); //if soil moisture sensor provides LOW value send LOW value to relay
  digitalWrite(13,HIGH); //if soil moisture sensor provides HIGH value send HIGH value to relay
  delay(400); //Wait for few second and then continue the loop.

Frequently Asked Questions

Why to use arduino?
“Connect sensor signal to relay module and finished… The code does only that thing anyway.”
The idea is to teach students how to make use of sensor data using Arduino. It will be useful to the students when they build something complex. We will also extend this project in our future videos.
Arduino was programmed or we have to programme it?
You have to program the Arduino and the programming (source code) is given in this post (see above). Also check: How to Connect an Arduino to PC or Laptop.
Error! it expected an initializer before WATER
First and second line are not being used in the program, so you can remove them. Also, there is an error in writing the variable name so replace AC WATER PUMP to ACWATERPUMP and it will work perfectly.
Which version of Arduino will work?
Since we are using only two pins, any Arduino will work for the project.
Which pump can I use, 12v or 5v?
We are using AC pump with the relay and recommend you for the same.
Can I make it for more than 1 plant?
Yes you can and we will show it in our next project.
Why did you killed the plant?
I am a plant lover, this is one of my hobby. So, you can’t expect me to kill a plant. The plant used in this video is safe and still at my home 🙂

Required Material to make it yourself

Vivek Verma

Pursuing Diploma in Electronics from RBS govt. polytechnic college, Bichpuri, Agra. He loves to play with electronics equipment. He makes electronics project for Learn By Watch and helps other electronics students to build electronics projects for science fairs and exhibition.

This Post Has 88 Comments

  1. plz help me!! When I am Uploading the program there is an error.the error states that “expected initializer before ‘WATER’. PLZZZ HELP ME

    1. Hi, there was a problem in first line. Replace AC WATER PUMP with ACWATERPUMP and the program should work. Infact you can remove first two lines of the program and it should work perfectly.

  2. what language you are using for the code

  3. Hii sir actually we are doing a project similar to your’s. That we can water a plant at regular intervals of time including detection of moisture. briefly, if you have a habit of watering plants daily at 5 pm even in your absence the motor should on automatically and water the plants. The amount of water should be watered to the plants are based upon the moisture content in the soil. Please help us sir as early as possible.

    1. You need to write code for this logic:

      If it’s 5 PM //read date / time from real time clock module ( )
      if water need water // read data from soil moisture sensor
      water the plant for 1 min // start the motor and stop it after 1 minute

      I hope it will be helpful. Let me know if you face any problem.

      1. Thank you so much sir…we are very happy for your help. If you don’t mine may we contact you through Gmail.
        My mail id is

          1. hi sir
            i want to supply water without using water sensor and i want to supply water daily at 9pm for 5mins. can u please give me the program for that i am very poor in can mail me at

        1. You can send us your mail id to my mail so that we can Contact you if there any urgent need. I assure you that your mail id will be safe and not be misused.

          1. Thankyou sir for your support

      2. Hi Vamsi, Please share your project story with us once you submit it. You can use images, videos, text etc and we will show it in our blog. You can submit your story at

    2. Sir what should i do if i want to use the combination of temperature and LDR sensor to water the plant ? . it is possible to make a code to arduino for this? . thanks for the answer sir.

      1. First, you need to learn how to connect temperature and LDR sensor to Arduino. After that, you need to utilize data received from these sensors to switch on/off water motor.

        Yes, this is possible with Arduino.

    3. Can I use 12 watt realy

  4. Plz help us sir as we have less time to submit our project

  5. Can i use dc pump of 5 to 12 v with relay

    1. A relay is an electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current. So, you need relay only if you want to operate AC devices. You can directly send the signal (current) to DC motor, you do not need relay for that.

      Let me know if this is helpful.

      1. Thank you for your support

        1. Hello sir, i use aquarium pump instead of the motor. Is it okay of i didnt use the relay?

          1. A relay is an electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current.

            So, if you want to give power to an AC device, use relay otherwise not.

  6. sir actually we are doing an project similar to this but we want to know how to change the angle of the water pipe if we have 2 or more plants so that it can water the plant which has less moisture.

    1. Sir please reply to my comment.

  7. sir, i followed your steps and connected all components and wrote program too..but it works opposite to what you have showed when i place soil moisture sensor in wet soil the motor is on and when i remove nothing happens plz help ..

  8. finally i solved my problem sir i just changed this values
    digitalWrite(13,HIGH); //if soil moisture sensor provides LOW value send LOW value to relay
    digitalWrite(13,LOW); //if soil moisture sensor provides HIGH value send HIGH value to relay
    compare this with original program
    this is working for me
    when i remove the sensor from the wet soil the motor is on state and off when i place it in wet soil
    anyway thx for program

    1. Hi. Can you help us? We are using this code but it didn’t work we are using a dc motor while the sensor is humidity sensor. Thankyou

  9. Hi can you add some code to control the power of the pump ?

  10. If i want to make more than plant which components should add? A higher motor?plz reply i’m working for school project.

  11. Sir,can we add more than two plant for watring system using one motor..plz give me a code for that..plz help us

  12. Instead of ac motor we use dc motor
    Is it working in automatic watering system for plants.
    When we don’t put soil sensor inside the soil water flow from pump but we put sensor inside the soil it will not work water is flowing continue instead of stoping
    Plz help me what can i do.

  13. Plz reply to my comment

  14. where and how to connect buzzer?

  15. Sir how to connect the rtc module on the circuit plsss explain it

  16. can i ask for a papers sir?thanks..

  17. sir may i get documentation of this project…?

  18. In a same area it will dry in some part and wet in some part.In such condition s how can use make of this sensor

  19. Great project. really enjoyed it. Could you do a project where you control this type of thing via wifi or app?

  20. Hi, I am receiving the reverse for the output…..when the soil moisture sensor is placed on dry soil then water is not flowing while water is flowing when the soil moisture sensor is placed in wet soil…How to overcome this?

  21. Hi, please help me. When I compile the program at the beginning there is no error but when I want to upload it to the board it says that it can not as if it did not detect it.
    Then, I got a 3-6 v motor and I connected it to a cell phone charger like in the tutorial but I checked all the connections and it does not work. I hope you can answer fast

  22. Hello
    I am trying to write a code for two soil sensors using python. i got it work for one sensors , but i could not do it for two sensors, so my question is there a specific loop for two sensors ??BTW, I am using Raspberry pi

  23. GPIO.setup(16, GPIO.IN)
    GPIO. setup(18, GPIO.OUT)

    GPIO.setup(7, GPIO.IN)
    GPIO.setup(7, GPIO.IN)

    while True:
    if GPIO.input(16)==1
    GPIO.ouput(18, True)

    if GPIO.input(7)==1
    GPIO.ouput(15, True)

    GPIO.setup(18, GPIO.OUT)

    GPIO.setup(15, GPIO.OUT)

  24. I have coded the arduino and done all the connections as shown in the video but the pump isn’t coming on.can I get some help on making it work

  25. Can anyone tell me wat is the order in which v have to connect the wire in the relay

  26. help me how to connect pizzo buzzer in the arduino and code for buzzer

  27. Can i use 5v dc or 12 dc motor seam relay

  28. Hi, I am a complete beginner. How to use this device for multiple plants at once? I mean if I use 2 motors and soil sensors, how to make it work for both?

  29. Hi
    I am Pratham
    The coding you gave in the videos not working can I ask for the correct coding I used 1 channel relay board instead of 4 channel relay board and other things are same
    Thank you

  30. how to link this device with a gsm module

  31. The things working reversly the water is being pumped when there is moisture and not being pumped when no moisture..please help me regarding this…

  32. send me the code of this project… pls..

  33. Good stuff ! I’m willing to do this project but I have small query. What if water from source get empty ? Because if there is no water to suck, the motor can fail or damage. How to overcome this small issue?

  34. Hi i am doing the project of automatic watering plants using arduino.
    I have done the connections according to the video given.
    I am sorry i did not understand the above codings posted in the above comments as i just have the very basic info. about coding done at school (c++).

    The problem is that when i give the power supply to both the arduino and the dc water pump, the pump starts working and also the sensor is dry. But now is the problem….

    The pump is running but according to the project the pump should stop when the sensor is dipped in water/wet soil. But that does not happen.

    When i take it out it stops. Again when i dip it in water and take it out it starts. This happens only a few times and then stops and nothing works.


    The pins for the coding is given below…
    The DO from the sensor – pin 9
    Pin 12 from arduino – IN1 of relay.

    Again please send me the correct coding and advice me if there is any problem.

  35. Sir I want interfacing soil moisture sensor and DC motor program

  36. should we compulsorily use the channels for this project?

  37. should we use only the 4 channels or we can use 2 channels also?
    please answer me quickly because i have to complete the project

    1. You can use 1 channel relay as we are using only 1 channel out of 4 channels available in 4 channel relay.

  38. In automatic irrigation system we’re we use the buzzer

  39. Sir, I’m making this project and I want to know the power supply of adruino board. So, please help me to get the power adapter for this project. Please suggest me. I’m very thankful to you for your kind support.

  40. sir i followed all the steps given above.there is no error while compiling and uploded completely but project is not working :(.please help me

  41. Sir how to know which variable should I put to describe the signal received from sensor

  42. Sir my circuit is complete but the motor does not stop even when water is full in the pot .
    I also don’t know which variable should I put to describe the signal received from the sensor. But still the programming is been uploaded.

  43. sir can i know all the circuit that use in this project

  44. sir can we use aquarium pump rather than ac motor??..what should be the code are we going to use??

    1. Same question, my aquarium pump runs at 5 watts of power and 110-120/220-240 voltage

  45. Can i use an aquarium.pump with 5 watts of power and 110-120/220-240 voltage

  46. where i buy the draining motor?

  47. Can this project be controlled via an Android app?

  48. i need to use this as a school project but am lacking its research proposal, can you please get me a copy

  49. Sir Iam getting reverse of that
    When I placing soil moisture into soil water is coming after removing sensor water is not coming
    It’s doing reversly i have to submit with in 2days provide me answer fastly

  50. Sir,
    This post helped me to develope my school project based andrino

  51. Hi
    Error shows me that
    ‘digitalread’ was not declared in this scope
    Plz help me to solve this

  52. Do we have to keep on taking the sensor out and in.??.

  53. how i use moisture sensor with LDR and write ardiuno code for this with its simulation

  54. hi admin i have some hours only to submit project on automatic plant watering system and the code you write above is done. but how i made simulation please help me if you can by sending video

  55. I want to buy this project is it available??

  56. can u give ur mobile number

  57. We want to buy this project for knowing details give ur mobile number

  58. pls help me i need help in coding i will pay for the code/project.
    thanks and regards
    my mobile no. is 9811112460

  59. pls help me i need help in coding.
    thanks and regards
    my mobile no. is 9811112460

  60. Sir can I use 1hp motor for this project with this program

    1. Yes, you can use any motor.

  61. sir, is it necessary to use 4 channel relay or simply we can use 1 channel relay

    1. You can use 1 channel relay also.

  62. Hey, hi
    I tried to use the same method and code, but it is not working for me
    The motor is not working in both the connection, i dont see any results

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