September 24, 2017

Automated Plant Watering with a Raspberry Pi

This post starts with two facts:

1. I have a penchant for killing plants.
2. People in Holland grow things really well indoors.

After reading about how well things can grow indoors, I started thinking that maybe automation was my path to healthy plants. So I decided to build the bare minimum - get a plant, a pump, and a water sensor. When the water sensor says "no water here", use the pump to put water there.

I also decided to run it all through a Raspberry Pi to as an excuse to interact with the RPi GPIO.

Here's how I did it!


  1. Raspberry Pi 3
  2. Soil Moisture Sensor
  3. Flexible Water Line
  4. 5V Relay
  5. 3-6V Mini Micro Submersible Pump
  6. TOLI 120pcs Multicolored Dupont Wire
  7. 5v Power Supply (Any USB Cable+ USB Wall Charger)


The first thing I did was make my 5V power supply from a usb cable. Using an old iphone cable, I cut the iphone side off and fished out a red and black wire. I soldered some sturdier wires to this, and plugged it into a wall adapter. Checking with a voltmeter, this gave me 5V output.

Now time for the GPIO.

RPi Wiring:

Following this GPIO layout:

Water Sensor -  plug the positive lead from the water sensor to pin 2, and the negative lead to pin 6. Plug the signal wire (yellow) to pin 8.

Relay - Plug the positive lead from pin 7 to IN1 on the Relay Board. Also connect Pin 2 to VCC, and Pin 5 to GND on the Relay board.

Pump - Connect your pump to a power source, run the black ground wire between slots B and C of relay module 1 (when the RPi sends a LOW signal of 0v to pin 1, this will close the circuit turning on the pump).

This diagram should capture the correct GPIO so long as you are using Raspberry Pi 3. Not shown is another power source to the RPi.

Hardware Setup:

Once the wiring has been completed, attach the flexible hose to the pump (I used electrical tape), and drop it into a jar of water. Attach the other end of the hose to your plant.

Now plug in all power sources (and make sure your Raspberry Pi is running some version of an operating system, like this one here).


Note: If you get the wiring exactly as described above, my code in the next section will work with no modifications.

There are two parts to this setup. One file controls all the GPIO and circuit logic, and the other runs a local web server.

All files:

GPIO Script

Let's start with the code for controlling the GPIO. This requires the RPi.GPIO python library which can be installed on your Raspberry Pi as follows:

$> python3.4 -m pip install RPi.GPIO

With that installed, you should be able to use the script found here.

You can test this is working correctly by running an interactive python session as follows:

$> python3.4
>>> import water
>>> water.get_status()
>>> water.pump_on()

This should print a statement about whether your sensor is wet or dry (get_status()), and also turn on the pump for 1s. If these work as expected, you're in good shape.

At this point you can also calibrate your water sensor. If your plant status is incorrect, try turning the small screw (potentiometer) on the sensor while it is in moist soil until the 2nd light comes on.

Flask Webserver

The next aspect of this project is to setup the web server. This code can be found here in a file called This python script runs a web server enabling various actions from the script described above.

You will need to keep in the same directory as described above, as well as You will also need a sub-directory called "templates" containing the html file here called main.html.

You will need to install flask, and psutil as follows:

$> python3.4 -m pip install flask
$> python3.4 -m pip install psutil

You will also need to create a sub-directory called templates, and place main.html in the templates directory.

Now run the following command command to start your web server:

$> sudo python3.4

Now if you navigate to the ip address of your RPi, you should see a web dashboard something like this:

Try clicking the buttons to make sure everything works as expected! If so, you're off to the races.

here's another great tutorial I followed on flask + GPIO

Run Website Automatically

Finally, you probably want the website to auto start when the RPi gets turned on. This can be done using a tool called cronjob, which registers your website as a startup command.

To do so, type:

$> sudo crontab -e

This will bring up a text editor. Add a single line that reads (and make sure to leave one empty line below):

@reboot cd <your path to web_plants>; sudo python3.4

Now when you reboot your pi, it should auto start the server. 


  1. This comment has been removed by the author.

  2. Can we use Solenoid valve instead of mini micro submersible pump, Sir?

  3. Same question sir.. i would like to use 12v solenoid valve to handle more power. Thanks in advance

  4. Yes you could use a solenoid valve, but the water would still have to be moved somehow. I have been thinking a gravity fed water line with a solenoid valve would be the best solution for something like a garden. Good luck.

  5. Sir, solenoid valve needs a 12v source. It is ok to connect it to the 5v relay module?

  6. Connecting the 12v source to 5v relay module, instead of 5v source that you use to the pump ...

  7. I don't know! Welcome to the joy of DIY :-)

    If it's 12V in the circuit the relay closes you should be fine though. If you're powering the relay itself with 12V, probably not good for the longevity of the component.

  8. Sir, for the Soil moisture what is the exact pin you use? The Digital Output or Analog Output?

  9. I'm getting a "ImportError: No module named psutil" when im trying to run the even i already installed the module psutil, any advice for this?

  10. I am testing the auto-water feature but the consecutive_water_count does not remain at 0 when I leave the sensor out on a napkin. I wanted to see how long the pump would keep activating until the consecutive_water_count reached 4 (starting at 0) - knowing fully that it would never reach because I don't have it in water.

  11. This comment has been removed by the author.

  12. Thanks for all the details. Can this setup be extended via WiFi as iot.what hardware/board can be used.

  13. Can you supply power to both the pi and the pump with the 5v? Or will the pi need to be plugged into main somewhere?

  14. Hi, How would this work if it was controlled from an Android App?

  15. Great project! I followed it and got it to work as well.... nice! Could you help me understand the soil humidity sensor though please? In the diagram a 3 pin sensor is used, in your vids you a different one with 2 pins... I have ordered such one, but I don't know how to connect and properly calibrate.

    1. Same problem here!! Did you ever figure it out?

    2. So I think the two wires you're seeing are just extensions of the circuit between the moisture pins... They connect to a tiny pcb with an LED on it where the sensitivity of the sensor is calibrated, and then 3 wires come from that tiny PCB back to the Pi. So its like in the diagram, but with wires running to the prongs of the sensor. Basically the sensor needs power (red and black) and a signal (yellow). Your red and black (VCC/GND) should connect to the input voltage, and yellow(OUT) should go to the RPi GPIO pin 8.

    3. Hi again! It turns out the potentiometer had 4 pin outputs but you only have to wire 3 to the raspbery pi as one is digital output (DO) and one is analog output (AO) as we are using digital hardware, you just wire the ground, VCC (power) and DO (digitaloutput) Thanks for your help though! Currently testing mine on the floor!

  16. Plzz someone explain those connections of youtube clearly

  17. I want to thank you for this script. I customized it a lot for my Garden. I did notice if you have the timer for water pump on long time and you end auto water. it does stop the script but the valve is still active and never shuts off. I added a line to cut off the pump prior to psutil to kill the script. I also added functionality to add more sensors. works sweet.

  18. templateData = template(text = "Auto Watering Off")
    GPIO.output(7, GPIO.HIGH) <<<<<<<<<<<<< Add this line to shut off pump
    os.system("pkill -f")

  19. For extra sensors edit make sure to have all the sensors hooked up to the pin numbers you specify

    def get_status():
    GPIO.setup(8, GPIO.IN)
    state1 = GPIO.input(8)
    GPIO.setup(10, GPIO.IN)
    state2 = GPIO.input(10)
    GPIO.setup(16, GPIO.IN)
    state3 = GPIO.input(16)
    val = state1 + state2 + state3
    return val