Published November 27, 2016 © GPL3+

ESP8266 Plant Grower

Use an EPS8266 and ThingSpeak to monitor your plant and use a grow light to boost your plant's height!

IntermediateFull instructions provided3 hours4,068

Things used in this project

Hardware components

Jumper wires (generic)

LED (generic)

9 blue, 3 red

SparkFun ESP8266 Thing - Dev Board

Relay (generic)

DHT11 Temperature & Humidity Sensor (4 pins)

Resistor 100 ohm

Software apps and online services

Arduino IDE

ThingSpeak API

Hand tools and fabrication machines

Soldering iron (generic)

Story

Overview

This started as a simple science project, but it has grown much greater than that. I was tasked with creating a grow box that would use blue and red light to increase plant growth. I decided to make it as cheaply as possible, while adding many other data streams. I used an ESP8266 Dev Board from Sparkfun and a DHT11 sensor for temperature and humidity readings. Here are a few pictures of the materials I used to make the plant "pots" and germinate them.

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The enclosure

I used a small cardboard box that was at least 1.5 ft. tall. I cut an 8 x 5 cm rectangle in the top to drop down the custom LED array I made. Then I hot glued white printer paper onto the inside walls.

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The electronics

I took an 8 x 5 cm perforated board PBC I got off of Amazon and laid down my 12 LEDS. Make your LED light ratio 3:1 blue to red. Now solder on a 100 ohm resistor attached to each LED, giving 12 total resistors. It should look like this when all done.

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Attach a simple USB A cable to the LED array and plug it into a wall adapter. Now connect that into a relay module. Wire up the DHT11 sensor to the ESP Dev Board along with the relay module. Log onto ThingSpeak and create an account. Make a new channel and set it for 2 fields, one temperature and one humidity. Then go over to the Channel API settings and get your write API. Paste that into the code and upload it to the ESP8266. Now just plug it in and let it do the work for you! Now you can log on from anywhere and check your plant's environment.

Code

Code

/*
 *  This sketch sends a message to a TCP server
 *
 */
//put your wifi network name here
#define SSID "ssid"
//put your wifi password here
#define PASS "pass"
#define API_KEY "API key here"
#define DHTPIN 13
#define DHTTYPE DHT11
#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>
#include "DHT.h"

ESP8266WiFiMulti WiFiMulti;
DHT dht(DHTPIN,DHTTYPE);

void setup() {
  pinMode(12,OUTPUT);
  digitalWrite(12,true);
    Serial.begin(115200);
    delay(10);
    dht.begin();

    // We start by connecting to a WiFi network
    WiFiMulti.addAP(SSID, PASS);

    Serial.println();
    Serial.println();
    Serial.print("Wait for WiFi... ");

    while(WiFiMulti.run() != WL_CONNECTED) {
        Serial.print(".");
        delay(500);
    }

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

    delay(500);
}


void loop() {
    const uint16_t port = 80;
    const char * host = "api.thingspeak.com"; // ip or dns

    float h = dht.readHumidity();
    delay(200);
  // Read temperature as Celsius (the default)
  float f = dht.readTemperature(true);
  Serial.println(h);
  Serial.println(f);
    
    Serial.print("connecting to ");
    Serial.println(host);

    // Use WiFiClient class to create TCP connections
    WiFiClient client;

    if (!client.connect(host, port)) {
        Serial.println("connection failed");
        Serial.println("wait 5 sec...");
        delay(5000);
        return;
    }

    // This will send the request to the server
    String cmd1 = "GET /update?key=";
    cmd1 += API_KEY;
    cmd1+= "&field1=";
    cmd1 += String((int)f);
    cmd1 += "&field2=";
    cmd1 += String((int)h);
    cmd1 += "\r\n";
    client.print(cmd1);
    //debugging
    Serial.println(cmd1);

    //read back one line from server
    String line = client.readStringUntil('\r');
    client.println(line);

    Serial.println("closing connection");
    client.stop();
    digitalWrite(12,false);
    Serial.println("wait 10 hrs...");
    delay(1000*60*60*10);
    digitalWrite(12,true);
    //wait 14 hours off
    delay(1000*60*60*14);
}