Smart Greenhouse: Watering by Soil Moisture

Three students in our Arduino programme developed this project after noticing that seedlings in the school garden dried out at weekends. When the soil moisture sensor drops below a set threshold, a small water pump runs for 5 seconds, and an LCD shows the moisture percentage and the time of the last watering.

The process

The team first measured sensor values in different soil types and drew up a table, setting the threshold based on those measurements. In the first prototype the pump ran non-stop; they found the problem was fluctuating sensor readings and wrote code that takes an average. The greenhouse frame was assembled with connectors printed on the 3D printer.

The project drew the most questions at the end-of-term exhibition and was tested in the school garden for a month. For the next version the team plans to add a Wi-Fi module that sends the data to a phone, so the school caretaker can monitor the greenhouse remotely and the seedlings stay safe over long weekends.