Raspberry Pi Pico makes sure your Christmas tree never goes thirsty

It is 21 December and if your tree is looking more beige than brilliant, this hack comes too late for you. YouTube’s most practical dad, Pater Practicus, has devised a Raspberry Pi Pico-powered thing to keep your Christmas tree looking brilliant and green all through the season by ensuring it gets the water it needs.

If you’re reading this in January, this project works equally well for any house plant, including all the dead ones I am currently looking at as I write this. By which I mean, it would work great for them had I not already killed them.

Thirsty tree hack

Pater Practicus decided to take a slightly more high-tech approach to keeping the family Christmas tree nice and green. He used a Raspberry Pi Pico to monitor the water level and keep needle drop to an absolute minimum. I swear my hoover sees more action in December than any other month of the year, so I am here for this hack.

The maker did the programming for this project on a Raspberry Pi 3

He started by sawing about an inch off the bottom of the Christmas tree trunk. Then he fitted it securely into a stand which also acts as a reservoir to give the tree a supply of water.

How does it work?

The Pico here had already been set up with MicroPython code for a previous project – it was running code to flash a red LED. The practical dad added extra code to read the data from a moisture sensor, making the LED flash when the water in the reservoir has run out. But he also wanted to get the green LED involved. He wrote some more MicroPython to make Pico show a green light when the program is running correctly. If he sees that lit up, he can rest assured that the Christmas tree is not going to go thirsty.

The moisture sensor is hanging from a couple of pins that are pushed into the Christmas tree’s trunk. It dangles at the height the water should always reach inside the tree stand. If the water is at the correct level, the red LED doesn’t light up, but if it dips too low, that red LED will start blinking and shame you into giving your thirsty tree some more water.

HackSpace magazine to the rescue

Pater Practicus adapted this project from an article he saw in HackSpace magazine. You should subscribe to it because it’s lovely and is packed with lots of practical project ideas for makers and tinkerers.

Here’s what the cover of the new issue looks like:

hackspace front cover issue 74

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Ashar avatar

Raspberry pi is underpowered for this task!
You need a 42U server with 256TB ram and. At least 2048 cores to be able to precisely control the number of water molecules needed for tree!

Reply to Ashar

Eff avatar

As I see the tree holder has a floating marker, which lifts up if there’s enough water in it. So this project is redundant in its current form.
Just wire up a relay and a small USB water pump, that will solve the watering/refilling issue.

Reply to Eff

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