Introduction: DIY Thirsty Plant Water Balloon

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Make an automatic watering device for your DIY Thirsty Plant with some easy to find items, simple electronics and Arduino! Prime the water bomb, position in the plant pot and wait for that Thirsty Plant moment to happen. If you can’t wait, disconnect the plant sensor and let the over watering commence. No plant will ever be thirsty again.

Step 1: Things You Will Need:

  • DIY Thirsty Plant Sensor

Household items:

  • Some sticks (twigs, lollipop sticks, pencils)
  • Some fixings (elastic bands, string, wire, glue)
  • Something sharp (pin, map pin, badge back, pencil)
  • Some small water bomb
  • 9 volt battery

Components from the Start Arduino kit (or bought separately):

  • Arduino Uno Servo Motor
  • 2 x Jumper wires
  • 2 x Crocodile clips
  • 9v Barrel Connector

Step 2: Making the Hardware

Attach Servo motor arm to stick with elastic band. This will be pushed into the plant’s soil.

Step 3:

Attach pencil to servo motor arm with elastic band

Step 4:

Connect servo to Arduino using jumper wires:

Red servo cable to 5v

Brown servo cable to GND

Orange servo cable to Pin 9

Step 5:

Connect two crocodile clips onto the GND and Arduino on the Thirsty Plant.

Step 6:

Connect two jumper wires from the crocodile clips from GND to GND and from Arduino to Analog Input 0

Step 7:

Attach your chosen sharp item to the end of sweep arm with blue tack, glue or even a hair braid band.

Step 8: Programming the Arduino

We’ve attached our DIY Thirsty Plant to analog input pin A0 so we’ll now need to use a sketch that takes a reading from that pin. In this sketch we’re reading the value from pin A0 and using that to trigger a servo arm sweep.

Download INO sketch for THIRSTY PLANT WATER BOMB here and open in the Arduino IDE on a computer and upload via USB to the Arduino.

Step 9: Testing the Hardware With Arduino

Attach power and disconnecting the plant sensor from it’s wires making sure they are not touching to simulate dry soil, after the 10 SECOND DELAY, does the servo arm move back and forth?

No? - go back and check you power and connections.

Yes! - time to try it out for real.

Step 10:

Disconnect Battery and place the Thirsty plant in the pot without the plaster sensor and wires not touching to simulate dry soil. Position balloon and servo striker in pot.

You may need to experiment with positions and angles of the servo and balloon. If using water, place Arduino in small plastic bag to prevent splashing, you might also want to place the plant in a tray, or on an old towel. Things are about to get messy.

Step 11: ​Things You Might Need to Tweak for the Perfect Pop:

• twisting of servo in soil

• angle of strike

• inflation of balloon

• balloon movement

• choice of sharp item

• position of sharp item on arm

• choice of fixings

• choice of sticks

Step 12: Editing the Arduino Sketch:

Open your sketch

To change the angle that the arm moves, change the angles marked below in red To change the delay between sweeps, change the pauses marked below in bold Remember to reload the sketch onto the Arduino.

// thirsty plant threshold reached (when dry)

if(analogRead(0) > thresh){

if(count < 3){ //Number of times the servo arm moves back and forth

for(pos = 0; pos < 20; pos += 1) { // goes from 0 degrees to 20 degrees

myservo.write(pos); // tell servo to go to position in variable 'pos'

delay(5); // waits 5ms for the servo to reach the position


for(pos = 20; pos>=1; pos-=1) { // goes from 20 degrees to 0 degrees

myservo.write(pos); // tell servo to go to position in variable 'pos'

delay(5); // waits 5ms for the servo to reach the position




} else {

count = 0;