How do you make a tree sweat?

By Maria Zammit | Posted: Thursday July 2, 2020

Worried that your holiday will be long and boring this July? Never fear, Science is here!

We’ve got a practical you can do during the break that can’t be done in your normal classes (awesome, I know!). You’ll need plastic bags (the ones you can get in the vegie section of your supermarket will do), a pebble for each bag, a twist tie or string for each bag, a kitchen scale or measuring jug, and the internet to check the temperature at your house.

How Do You Make A Tree Sweat?

Aim: To find out what makes trees lose the most water.


1. Put a plastic bag over a leafy branch. Include as many leaves as possible in it.

2. Place the pebble in the corner of the bag to weigh it down. Tie the bag securely with string or the twist tie.

3. After 24 hours, collect the water produced by the leaves. Measure the amount of water – you can do this by using a measuring jug, or weighing the water (1g of water equals 1 mL).

4. Find out how warm the weather was at your house – is good website that you can use to find out the weather for Dunedin.

5. Repeat this every day for a week.

Results: Create a graph comparing the amount of water the tree lost with the temperature on the day.

Conclusion: Did you see any link between the temperature and the volume of water?

Discussion: Why do you think you saw those results? How could you make your experiment more accurate?

Extension. Instead of comparing the affect of temperature, you could find out if some trees lose more water than others.