There is nothing new about talking to plants – people have been doing it for at least 150 years to get them to grow faster – but you don't get an instant reply and you could never call it a watertight gardening strategy.

But what if a plant could give you immediate feedback on how it was faring? Imagine if a tree could tell you the moment it was getting thirsty or let you know how it was handling a hot spell or a cloudy patch?

Two months ago, Dr Melissa Neave, a senior lecturer in sustainability and urban planning at RMIT, and Dr Scott Rayburg, a senior lecturer in water, environment and sustainability at Swinburne, embarked on a project that allows trees to do just that.

Dr Melissa Neave and Scott Rayburn with one of their 'sap sensors' on a tree at CERES Environment Park. Credit:Eddie Jim

They attached to the trunk of nine trees at CERES Community Environment Park in East Brunswick a device that continuously measures the rate of water flow both up and down each tree. The resulting data tells Neave and Rayburg – long before there are dropping leaves or other visual cues – when each tree is getting water-stressed. Conversely, it also reveals when a tree has received more water than it needs.