Arduino moisture sensor sketch

moist.ino

#include <Arduino.h>
#define MOIST_PIN_1 A5
#define MOIST_PIN_2 A4
#define MOIST_PIN_3 A3
#define MOIST_PIN_4 A2
#define MOIST_PIN_5 A1

#define PWRBTN 7
#define RELAYPIN 5

byte lastButtonState = LOW;
unsigned long debounceDuration = 50; // millis
unsigned long lastTimeButtonStateChanged = 0;

int incomingByte = 0;

char subject1[] = "Philodendron"; // TODO: reorder
char subject2[] = "Alocasia";
char subject3[] = "Monstera";
char subject4[] = "Basil";
char subject5[] = "Pilea";

void setup() {
  pinMode(PWRBTN, INPUT);
  pinMode(RELAYPIN, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // Receiving instruction from Serial port
  if (Serial.available() > 0) {
    incomingByte = Serial.read();
    digitalWrite(RELAYPIN, HIGH);
    delay(1000);
    measure_moist(MOIST_PIN_1, subject1);
    measure_moist(MOIST_PIN_2, subject2);
    measure_moist(MOIST_PIN_3, subject3);
    measure_moist(MOIST_PIN_4, subject4);
    measure_moist(MOIST_PIN_5, subject5);
    digitalWrite(RELAYPIN, LOW);
  }

  // Receiving instruction from Button
  if (millis() - lastTimeButtonStateChanged > debounceDuration) {
    byte buttonState = digitalRead(PWRBTN);
    if (buttonState != lastButtonState) {
      lastTimeButtonStateChanged = millis();
      lastButtonState = buttonState;
      if (buttonState == LOW) {
        digitalWrite(RELAYPIN, HIGH);
        delay(1000);
        measure_moist(MOIST_PIN_1, subject1);
        measure_moist(MOIST_PIN_2, subject2);
        measure_moist(MOIST_PIN_3, subject3);
        measure_moist(MOIST_PIN_4, subject4);
        measure_moist(MOIST_PIN_5, subject5);
        digitalWrite(RELAYPIN, LOW);
      }
    }
  }
}

void measure_moist(int pin, char name[]) {
  int moistV;
  long humanReadableValue;
  delay(500);
  moistV = analogRead(pin);
  // Theorical values: map(moistV, 203, 1023, 100, 0);
  humanReadableValue = map(moistV, 220, 750, 100, 0);
  Serial.print("Subject: ");
  Serial.println(name);
  Serial.print("> Moisture level (%): ");
  Serial.println(humanReadableValue);
}

Measurement is made at button click.
Waiting for relay to be able to power off sensor at idle time.

Update: Added relay + remote activation

Added more sensors