Arduino example for using the HiGrow board based on ESP32 as a server, so you can check in on your plant to see how it's doing

HiGrow_server.ino

/*
* Arduino example for using the HiGrow board based on ESP32 as a server, so you can check in on your plant to see how it's doing
*
* Details on the hardware and how to use it can be found on:
* http://flashgamer.com/blog/comments/higrow-esp32-moisture-and-temperature-sensor#capacitive
*/

#include "DHT.h"
#include <WiFi.h>

#define DHTTYPE DHT11
const int LEDPIN = 16;
const int DHTPIN = 22;
const int SOILPIN = 32;

const char* ssid     = "yourssid";
const char* password = "yourpasswd";

WiFiServer server(80);
DHT dht(DHTPIN, DHTTYPE);

int waterlevel;
float humidity;
float temperature;
float hic;
unsigned long nextMeasurement;

void setup() {
  Serial.begin(115200);
  pinMode(LEDPIN,OUTPUT);

  // setup wifi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected.");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

  // start the server
  server.begin();
  // Turn LED off to show that we're connected
  digitalWrite(LEDPIN, HIGH);
}

void loop() {
  // always maintain the wifi
  maintainServer();

  // Update measurements only each second
  unsigned long currentTime = millis();
  if ( currentTime > nextMeasurement )
  {
    waterlevel = analogRead(SOILPIN);
    humidity = dht.readHumidity();
    temperature = dht.readTemperature();
    hic = dht.computeHeatIndex(temperature, humidity, false);

    nextMeasurement = currentTime + 1000;
  }
}

void maintainServer() {
  WiFiClient client = server.available();   // listen for incoming clients

  if (client) {                             // if you get a client,
    Serial.println("New Client.");           // print a message out the serial port
    String currentLine = "";                // make a String to hold incoming data from the client
    while (client.connected()) {            // loop while the client's connected
      if (client.available()) {             // if there's bytes to read from the client,
        char c = client.read();             // read a byte, then
        Serial.write(c);                    // print it out the serial monitor
        if (c == '\n') {                    // if the byte is a newline character

          // if the current line is blank, you got two newline characters in a row.
          // that's the end of the client HTTP request, so send a response:
          if (currentLine.length() == 0) {
            // HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
            // and a content-type so the client knows what's coming, then a blank line:
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println();

            // the content of the HTTP response follows the header:
            client.print("<p>Moisture: ");
            client.print(waterlevel);
            client.print("<br>");
            client.print("Humidity: ");
            client.print(humidity);
            client.print("<br>");
            client.print("Measured temp: ");
            client.print(temperature);
            client.print("<br>");
            client.print("Perceived temp: ");
            client.print(hic);
            client.print("</p>");
            client.print("<p>Click <a href=\"/H\">here</a> to turn the LED off.<br>");
            client.print("Click <a href=\"/L\">here</a> to turn the LED on.</p>");

            // The HTTP response ends with another blank line:
            client.println();
            // break out of the while loop:
            break;
          } else {    // if you got a newline, then clear currentLine:
            currentLine = "";
          }
        } else if (c != '\r') {  // if you got anything else but a carriage return character,
          currentLine += c;      // add it to the end of the currentLine
        }

        // Check to see if the client request was "GET /H" or "GET /L":
        if (currentLine.endsWith("GET /H")) {
          digitalWrite(LEDPIN, HIGH);               // GET /H turns the LED on
        }
        if (currentLine.endsWith("GET /L")) {
          digitalWrite(LEDPIN, LOW);                // GET /L turns the LED off
        }
      }
    }
    // close the connection:
    client.stop();
    Serial.println("Client Disconnected.");
  }
}