Homemade LED growing light system using Arduino

Introduction

A few months ago, we started with a simple IKEA plant growing kit.
This was perfect to begin our indoor gardening project. Winter was coming soon, so our young plants needed a warm space inside to survive. It worked great! Until winter really kicked-in. The days became shorter and our plants were not able to grow at the same rate anymore.
Planting new seeds was useless as there was simply not enough sunlight for the plants to grow. Some sort of growing light solution was needed.
It was very easy to upgrade our IKEA plant growing kit and a seed starter. We purchased a LED strip and used an old Arduino we had laying around in order to create a professional working growing light system for a couple of dollars.

We did a lot of research regarding the use of (artificial) lights for seeds and plants.
I can assure that this can become a very long discussion, as it is an extensive topic in the gardening community. However, for the sake of this tutorial, I will keep it short.

Do not get me wrong. We definitely believe in the effect of having natural light and we find it important to grow plants outside during spring and summer. Nothing beats the natural way of doing, especially when living a sustainable life.

 

Full spectrum and growing lights

We are able to divide artificial lights into two main groups. On one side you have the “full spectrum” lights, and on the other side there are “growing lights”.

Full spectrum lights, which is a marketing term by some manufactures, generally offers light from the entire spectrum. Meaning that it can go all the way from Ultra Violet (UV) to Infrared (IR), and everything in between. The theory behind these types of lights is to emulate the most natural light possible.

Growing lights are a combination of only two colors of the spectrum. They focus on (deep) blue and (deep) red, which is being combined and forms some sort of magenta color.
The goal here is to use the most important parts of the spectrum in order to optimize plant grow and eliminate “useless” light photons.
According to some studies, each part of the spectrum is driving different functions of the plant.

 

What did we choose, and why?

Each method has their pros and cons. Choosing a light system that suits you will depend on what you find important.
Conduct some research on your own, so you can make the best decision for you.

At the end of this post, you can find some interesting links if you want to learn more about the light spectrum and the researches that have been done.

Personally, we went for the growing light option as you might have seen from the article image.
We are combining 2 red lights and 1 blue lights in our LED strip.

There are several reasons for this:

Cost effective:

Light consumption in LED lights is (partially) defined by the RGB colors that are being used.
White light with the highest brightness will consume more electricity as the RGB spectrum is completely utilized.
It speaks for itself that using only reds and greens result in a lower energy consumption.

Future vision:

Overpopulation is causing a lot of farmland to disappear. In addition, the rising sea levels due to global warming is making some countries think. The Netherlands for example, is one of the world leaders in indoor gardening. Several companies are investing in research and infrastructure, allowing them to grow their most consumed plants indoor for 365-days a year [we can recommend the following documentary: The rise of vertical farming – (VPRO documentary – 2017).].

Looking at these companies, we noticed that all of them are using the red/blue combination.

PS: NASA is using the same techniques when experimenting with growing plants on Mars.

Some other benefits of choosing RGB LED lights are:

  • Long lifespan;
  • Low heat production;
  • Possibility to fine-tune the spectrum afterwards.

 

Arduino tutorial

Material/Tools

  • WS2812B Smart/addressable LED pixel strip (1m, 60 LEDS)
  • Arduino (Uno, Mega, etc…)
  • Soldering iron
  • Cables
  • Old USB cable
  • Powerbank (solar powered)
  • IKEA seed starter or growing set (optional)

Cutting LED strip

Measure your LED strip and cut it into three equal pieces. Make sure that you have enough coper on both sides of the strip.
The LED strip I used was 1m long and had 60 lights in total. Each part is 20 pixels long.

 

Soldering the parts together

After cutting your LED strips, it is time to start soldering them together. Normally each part should have a ground, data and power connection.

Connect as follows:

  • Ground (GND) – to – Ground (GND)
  • Data in (Din) – to – Data out (Dout)
  • Power (3V or 5V or 12V) – to – Power (3V or 5V or 12V)

 

Connect to Arduino a power source

Use an old USB cable, strip it and find the ground, and power wires.
Note! Colors or the wires might differ from brand to brand. Test this before with a multimeter or with just one LED light.

Connect the ground wire of the USB to the ground of the LED strip (on the data in side).
Repeat this for the power wire as well.

Connect the ground wire of the LED strip (on the data in side) to the ground of the Arduino.
Connect the data in (Din) wire of the LED strip to one of the available ports on the Arduino (13 for example).

 

Upload code to Arduino

Use the following code and flash it onto your Arduino.

 

Testing

Connect the USB cable and the Arduino to your powerbank and test the connection.
Normally you should be able to see all LEDs lighting up.

 

Conclusion

From our experience, we noticed that the growth is indeed a lot more optimal when using our homemade LED growing lights.
The combination of 2 red vs 1 blue seems to be our sweet spot.
No heat is being produced from the LED lights and we run them for around 4 to 6h per day (at night). During the day we are charging our powerbank using solar energy, making it a zero-footprint light system.

This short blog post was just the tip of the iceberg.
A lot of research has been done by other people as well. Try and conduct some research on your own in order to find a solution that suits your needs.

Hopefully this tutorial was a bit helpful.

If you have questions, feel free to leave a comment and we will get back to you.

 

Some interesting links to researches and documentaries about this topics:

 

 

 

 

 

 

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Yoran
Written by Yoran
Small town boy, who grew up next to a farm and with a big garden. Recently moved to the big city and discovering his passion for gardening in small spaces. Engineering background helps thinking outside the box.