Build a budget IoT Grow-box with your Raspberry Pi

by Alex Ellis

In this guide I'll show you how to build an Internet of Things (IoT) grow-box that will share the progress of your plants growing live on the internet via Twitter.

This is a perfect project for the summer holidays or for a weekend project for kids and adults too.

Official Raspberry Pi PiNoir camera shooting in infra-red

If you already have a Raspberry Pi camera it should only cost you a couple of pounds or dollars to complete the project. I've started off growing cress in some compost and a plastic saucer, but what will you grow?

Where did the idea come from?

I've been making timelapses with my Raspberry Pi since the first camera module was released several years ago, but I always had the same problem - positioning. I could never find a good way to mount the RPi camera which resulted in my using copious amounts of sticky tape.

To cut a long story short - this often left permanent marks on my windows or lots of sticky residue before falling off or moving.

Last year I tried broadcasting seeds growing on the Internet via Twitter. This worked well and was even re-tweeted by the Raspberry Pi Foundation but the camera was just propped up on a peg. It could have moved and ended up and sharing the inside of our house instead.

I decided to hack a stackable storage box which I bought at a store in the UK called Poundland (everything costs £1 which is around a dollar).

I fixed the camera onto the storage box with screws meaning

we get a fixed position and have created a kind of photo studio.

This is a budget build, so there were no special jigs or colourful slices of laser-cut acrylic. I used a tiny finger drill I bought on eBay to make mounting holes for the Pi Camera and Pi Zero. Once I knew where the camera's lens was going to be positioned I drilled a hole then widened it with a pair of scissors.

Be especially careful if you are handling scissors or a hand-held electric drill.

Build your own

Materials:

  • Stackable plastic box (£1 / $1)
  • Raspberry Pi ZeroW w/ SD card
  • Power adapter
  • Raspberry Pi camera - colour or NoIR
  • Assorted screws and nuts to fit Pi and Camera

If your power adapter doesn't reach from the plug to where you want to place your grow-box then you can use an extension lead or a power adapter with a longer cord.

Software

The code for the grow-box is written in Python using the picamera, tweepy and PIL (Python Imaging Library) modules.

The code does the following:

  • Takes a photo in 1080p resolution
  • Overlays the current CPU temperature in the top left of the image
  • Saves the images to the SD card
  • Tweets the photo including a short message
  • Deletes the image from the SD card

I've provided a cron configuration to run every 60 seconds between 8am and 8pm every day, but you can tweak that.

Before you can get Tweeting you'll need to sign up for a Twitter Application / Developer code so that your Pi can Tweet on your behalf. If you've ever used a project with tweepy before then you can re-use the same token and secret. Just fill out the details in a file called config.py - you'll find a sample called config.example.py that you can copy from.

Fork or Star the code on Github so you can follow the README later when you're ready to start the build.

What next?

Fine-tuning

Once you have everything up and running you may need to change the focus of the camera so that your plants look clear and sharp. There are a number of ways of changing the focus of the lens - either with a pair of pliers or a large eraser.

Apply gentle rotational pressure until you feel the glue holding the lens in position give way - you can now turn left or right to bring your plants into focus.

A good way to get a live preview of your camera is to follow my YouTube live streaming guide - it only takes around 5-10 minutes to get started.

Deciding what to grow

Here's some suggestions for what you could grow indoors at any time of year:

  • Dried peas
  • Cress
  • Lettuce or rocket (arugula in the US)
  • Mustard

If you want to experiment you could also try planting pop-corn, lentils or apple seeds.

You could test compost against wet kitchen roll to see which yields a better crop.

Update 03 July 2017: Here are pea shoots (Pea Serge variety) which produce edible leaves when young:

Sharing

When you're ready and your grow-box is busy tweeting away - you can share it with your friends and family and keep and eye on when your plant is ready.

Here's an example of a Broad Bean germinating by Richard Gee who is one of my Twitter followers:

Extending the project

Here are a few ideas for extending the project:

  • Record environmental data on each photo

If you pick up a Pimoroni Enviro-pHat you can record temperature, humidity, light and pressure at the same time. A Bosch BME280 sensor can be extended on dupont wires and placed inside the box to take more accurate readings.

  • Automatic watering

With a low voltage water pump and a cheap rain-sensor you can create a feedback-loop and automatically water your seeds when they get dry.

  • Use a grow-light

You could buy an infra-red growing light so you can take photos at night, or get your crop quicker

  • Use other social media channels

If you're a member of a Slack community or have an Instagram account - maybe you extend the code to upload there instead.

Keep learning

If you would like to learn about more Raspberry Pi projects I have a series here:

You can also live stream to YouTube or record a timelapse.

If you'd like to learn how to create your own blog and host it on a Raspberry Pi checkout my self-hosted blog series:

Follow me @alexellisuk and get in touch on Twitter or in the comments section below with your questions and suggestions.

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