When Etienne Deneault was searching for a new Raspberry Pi project and, at the same time, wondering what to do with his broken Weber BBQ, he hit on a great idea. Having seen how other makers had converted old BBQs into planter box gardens, the seeds of an idea were planted.

“The convergence of the two ideas was what motivated me to build it,” he explains. “I also liked the ‘Americana’ influence captured by the use of the Weber grill. Weber is an icon of the American backyard BBQ culture; I like that it can continue to serve up food for us humans to enjoy."

Horticultural haven

Armed with his elderly BBQ and a Raspberry Pi-based Smart Garden System Kit (SGS v1) from SwitchDoc Labs, Etienne set to work to inject new life into the old grill. He needed to make modifications to both the Smart Garden System Kit and the BBQ – for example, the Smart Garden Kit was designed for indoor use, so Etienne needed to ‘weatherise’ it, and the BBQ had to be transformed into a planter box with an adequate drainage system, which required some carpentry and plumbing skills to be called into action. This didn’t hold Etienne back, however: “I found a tutorial video on building planter boxes and applied some of the knowledge that I learned watching it. I have built significantly more complex carpentry projects than this one in the past.”

Testing the watering system before the final build

Once his planter was ready to propagate, the technical side came into play. “The Smart Garden works essentially in an ‘event-based’ model,” he says. “It uses a module in Python called APScheduler to create recurring events. For example, it will ‘check’ the soil moisture sensor level every 15 minutes. If the return of this ‘check’ is below a predetermined moisture threshold, then an ‘alarm’ is created to water the plant.” The tank capacity is also monitored by an ultrasonic sensor which again triggers an alarm when the water level gets too low. However, the other sensors – including air quality, sunlight, and temperature – are for information purposes only, so no alarms are required.

The project required a lot of soil moisture sensors

Etienne did some tweaking to the Python code to fit his specific needs in the extreme Las Vegas environment – for example, he changed the soil moisture check to every five minutes instead of 15, so that plants wouldn’t have to wait too long to be watered, and he changed the length of watering time so that they got enough water. He also tells us that he “used a longer ‘dumb’ moisture sensor to measure deeper into the soil than the moisture sensors of the Smart Garden can reach. The soil moisture at seven inches deep was not high enough.”

Feeling hot, hot, hot...

So, what’s Etienne growing and how are the plants faring? Having originally planted tomatoes and peppers a little too late, he soon found that the Las Vegas summer desert temperatures proved too much for his young vegetables and they succumbed to the extreme heat (up to 46°C!)

 Etienne surrounded the metal frame of the BBQ with wooden panels

That said, he’s now feeling more confident: “Now that the heat of the summer is passed, I have planted again for the fall season. I am growing mini yellow squash, mini cucumbers, and a poblano pepper plant. I am not late planting this time around so I am optimistic that the result will be good.”

 An ultrasonic sensor measures the tank’s water level

Feedback from family and friends has been very positive, and it has educational benefits too. “They also appreciate that I do these projects, not only because I enjoy them, but to expose my son to STEAM educational opportunities,” explains Etienne. “I can clearly see the evolution of his questions over time, reflecting his increasing understanding.” He adds, “A mixed vegetable grilled antipasto is delicious eating for a BBQ; this Weber won’t be cooking it, but it might provide some of the ingredients!” It’s an excellent and pleasurable project where you should (extreme temperatures permitting!) have something to show for your labours at the end – why not try it yourselves?

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