Published November 10, 2025

Automated Plant Lights

Adaptive purple LEDs that effortlessly provide a source of nutrients for indoor plants without hassle of turning on / off these LEDs.

BeginnerShowcase (no instructions)73

Things used in this project

Hardware components

Particle Photon

Photo resistor

LED Strip, NeoPixel Digital RGB

Resistor 10k ohm

Jumper wires (generic)

Breadboard (generic)

Male and Female Pin Header Connectors

Software apps and online services

Particle Build Web IDE

Hand tools and fabrication machines

Soldering iron (generic)

Solder Wire, Lead Free

Plier, Cutting

Story

Background: Plants primarily use a combination of red and blue light to photosynthesize. Since sunlight is a spectrum of all colors, the chlorophyll absorb certain wavelengths of light that can be found in red and blue colored lights. By combining the frequency of red and blue lights, purple lights will provide the optimal source of nutrients to support plant photosynthesis. This contrasts our everyday lights because they do not provide the same special combination and intensity.

Purpose&Function: The LED strip will automatically turn on once the photoresistor senses that the plant’s environment is too dark OR if the program recognizes that it is currently past sunset time. By implementing automated plant lights will ease my own responsibilities of having to turn the plant light on and off + moving the plant around the house depending on the sun’s position.

Code

Home Automation Project: Automated Plant Lights Code

Home Automation Project: Automated Plant Lights Code

C/C++

Setting up a function as callTime
Using the time class, it will find the current hour and current minute
Converts everything to minutes and returns the minute value.

Loop calls for the analog return value from the photoresistor.
Uses that same value to checks it through the conditionals set
450 is the brightness value, values under 450 will turn on the LEDs.
Values above 450 will require program to check for current time to check if the source of light is from the sunlight or from our synthetic room lights.

// This #include statement was automatically added by the Particle IDE.
#include <neopixel.h>

// global variables - avoid as much as possible
int led = 4;
int val= 0; 
int analogPin= A5; 
int currHour=0; 
int currMin=0; 
int currTime= 0; 
int sunset= 1110; 
int timeResult=0; 

SYSTEM_MODE(AUTOMATIC);

// IMPORTANT: Set pixel COUNT, PIN and TYPE
#if (PLATFORM_ID == 32)
// MOSI pin MO
#define PIXEL_PIN SPI
// MOSI pin D2
// #define PIXEL_PIN SPI1
#else // #if (PLATFORM_ID == 32)
#define PIXEL_PIN D2
#endif
#define PIXEL_COUNT 8
#define PIXEL_TYPE WS2812B

Adafruit_NeoPixel strip(PIXEL_COUNT, PIXEL_PIN, PIXEL_TYPE);

void setup() {
  pinMode(led, OUTPUT);
  Time.zone(-5); 
  strip.begin();
  strip.show(); 
}

int callTime(){ 
currHour= Time.hour()*60; 
currMin= Time.minute(); 
currTime = currHour + currMin;
return currTime; 
}

void turnPurple(uint8_t wait){ 
     uint16_t i, j;
     
    for(i=0; i<strip.numPixels(); i++) {
      strip.setPixelColor(i, 255, 0, 255);
    }
    strip.show();
    delay(wait);
}

void turnOff(uint8_t wait){ 
     uint16_t i, j;
     
    for(i=0; i<strip.numPixels(); i++) {
      strip.setPixelColor(i, 0, 0, 0);
    }
    strip.show();
    delay(wait);
}
   
    
void loop() {
val= analogRead(analogPin); 

 if (val >450){
     timeResult = callTime(); 
     if (timeResult > sunset){ 
      turnPurple(0); 
 }else{ 
     turnOff(0); 
 }
}else{ 
   turnPurple(0); 
    }
}