Using the Grove Smart Plant Care Kit for Arduino

In "The Everyday Tech Growing the Future of Food" episode for The Engineering Edge Podcast, I decided to try the Grove Smart Plant Care Kit for Arduino - a kit designed to monitor the moisture levels of soil and water plants.

I use basil a lot in my cooking. It's a herb I can manage to usually keep alive - until I go away for a few weeks. And then it shrivels up and dies due to lack of water.

As I had been learning about The Everyday Tech Growing the Future of Food for The Engineering Edge Podcast, I decided to try the Grove Smart Plant Care Kit for Arduino (174-3224) a kit designed to monitor the moisture levels of the soil and water the plants as required.

It comes with a moisture sensor and water flow sensor - as well as a 12V water pump - which I wanted to use. Also included in the kit are a temperature and humidity sensor and a sunlight sensor - which I decided to leave for another day.

It also comes with an OLED display, a rotary encoder and a button - used for setting the parameters.

There's also a base shield that plugs into an Arduino (715-4081) (not supplied).

The instructions are relatively simple. Although I was amused by the "rule of thumb" translation:

I set up the Arduino and sensors without procuring any pipe. It all seemed to work OK. But when I got the pipe, I decided I didn't need the temperature and humidity sensor or the sunlight sensor and didn't plug them in. I then couldn't get the system to work! Am still not quite sure why it worked again when I plugged them in - I didn't bother to investigate.

The system worked well over the fortnight that I left it. However, one thing I had overlooked. The moisture sensor is at the top of the plant, and I watered the plant from the base. Although I had limited the amount of watering to about 0.1 litres, the sensor checked every 30 mins or so. And it takes longer than that for the moisture to travel up the soil in the plant to the sensor - so it still registered "dry" when the base was flooded. Fortunately, I had foreseen a water emergency and put the plant inside a larger bowl AND on a tray.

When I pulled the sensor out after a few weeks, I noticed it had begun to corrode:

Verdict:

The system is a good idea, it seems to work well, although probably not worth the effort just for one basil plant! Also, it needs to be plugged in - both for the 12V pump and the Arduino - all the time. So it needs to be near an electrical socket.

The moisture sensor and pump did what I expected (human error aside), and it seems possible to change the programming to take in to account the sunlight, temperature and humidity.

Putting this in an enclosed environment, like a greenhouse, would probably be ideal. I'm a little concerned about the corrosion on the moisture sensor - but the other sensors don't sit in a damp environment, so shouldn't have this problem. Also, once this system has been used for a while, the other sensors could be used to calibrate the watering required - and so the moisture sensor may not be needed after that.

If I had a greenhouse, I'd be using this.