Why do random characters fill up my Arduino LCD Display?

Question

I am making a water pump system for plants and I am running into trouble with displaying my Temperature and Humidity values. I am using a 20x4 LCD, Arduino board uno, Capacitive soil moisture sensor, 5v DC water pump, DHT22, and a single relay. When the motor is on, the display first shows the values as expected. Then, all of a sudden random characters fill and move across my screen. When I don't connect my motor to the Arduino, the values show up on the LCD as expected. Please do leave comments so that I am able to improve my code. Thanks.

//Libraries
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include "DHT.h"

//Pins Used
#define DHTpin 2
#define DHTtype DHT22

//Initialization
DHT dht(DHTpin, DHTtype);
LiquidCrystal_I2C lcd(0x3F, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);





int sensor_pin = 0; // Soil Sensor input at Analog PIN A0
int pinValue;
int output_value ;
void setup() {
  // put your setup code here, to run once:
  pinMode(3,OUTPUT);
     Serial.begin(9600);
   Serial.println("Reading From the Sensor ...");

  lcd.begin(20, 4);
  delay(4000);
}


  // put your main code here, to run repeatedly:

  void loop() {
  lcd.clear();
  dht.begin();

  float humid = dht.readHumidity();
  float temp = dht.readTemperature();

  lcd.setCursor(0, 2);
  lcd.print("Temperature: ");
  lcd.print(temp);
  lcd.print("C");

  lcd.setCursor(0, 3);
  lcd.print("Humidity: ");
  lcd.print(humid);
  lcd.print("%");



 pinValue = analogRead(sensor_pin);
 output_value = map(pinValue,700, 300,0,100);

  Serial.print("Mositure : ");
  Serial.print(output_value);
  Serial.println("%");
   if(output_value> 0 && output_value <= 51){
    digitalWrite(3,LOW);
    lcd.setCursor(0,0);
    lcd.print("ON");
    lcd.setCursor(0,1);
    lcd.print("MOISTURE VAL: ");
    lcd.print(output_value);
    lcd.print("%");



    delay(1000);

     }else if(output_value > 51 && output_value <= 100){
      digitalWrite(3,HIGH);
      lcd.setCursor(0,0);
      lcd.print("OFF");
      lcd.setCursor(0,1);
      lcd.print("MOISTURE VAL: ");
      lcd.print(output_value);
      lcd.print("%");



      delay(1000);

     }
     delay(1000);
}

EDIT (1)

Here are some pics of the circuitry and the LCD message. If you find these pictures to not be helpful, I can sketch this circuit. Thank You.