Thirsty Flowers


With the freedom, books, flowers and the moon, who could not be happy?

Oscar Wilde

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I have been wanting to do this with Patronus A for quite a while, but always kept forgetting white flowers. Then a couple of weeks ago we had some friends over and they brought white flowers. No excuse for me then! Patronus A about a year ago was obsessed with trees and flowers, how they grew, how they drank water, what happened when it rained and the sun was out. 

This activity is a fantastic visual way to teach them the biology of the process. By using water with food colouring in it, over the course of a few days the flowers begin to change into whatever colour water it is sucking up. It's a pretty cool experiment! 

We tried it with different colours, and two types of flower also. Over the course of a week and a half we saw which colours worked quickest, brightest, which didn't really work. Whether that was because we didn't put enough food colouring? We talked about how they change colour and how flowers suck up the water to the leaves. 


Key biology words to use when doing this with your little feet: 


Refers to the system of tubes that transport and is responsible for the movement of water and nutrients throughout the flowers and plants. When flowers are cut from their roots the xylem will continue to pull up the water to feed the plant for a while. If you put food colouring in the water, then the flower will slowly change colour as the liquid reaches it. 

Capillary action:

Process of how a liquid, like water, moves up something solid, in this case a tube. This is able to happen when three forces work together; cohesion, adhesion and surface tension. Together they create a capillary action. 


The process of two things sticking to each other, like two sides of a strip of velcro. 


Water droplets stick together. Adhesion is when a water droplet (molecules) sticks to the side of a tube and begins to move upwards. That water droplet will then pull up the next one and the next one in a long chain. 

Surface Tension:

when water droplets hold together tightly at the surface. This makes the surface of the water more solid then the rest of the water. This helps hold the water at the top so it can move it upwards with capillary action. Surface tension is how a paper boat will float on the top of the water, or how an insect can stand on the top of the water. 

Chrysanthemums (I think?!)

Chrysanthemums (I think?!)

White alstroemeria (i think?!)

White alstroemeria (i think?!)

What you will need: 

  • White flowers (why not try some snowdrops, they are everywhere right now)
  • Glass jam jars
  • Water
  • Food colouring (we used Wilton's)
  • Patience (about 1 week!)


  1. Fill up your jam jars with water.
  2. Put a drop of food colouring in each jam jar. One colour per jar. 
  3. Using scissors, diagonally cut the stem of some flowers. Enough to go in each jar. One flower per jar is enough. 
  4. Leave them on a window sill for a few days and watch them change colour!

What we discovered?

We discovered that the darker colours - blue and purple had the best effect on the white Chrysanthemums and that both these colours simply come out on the petals as blue.  Red, yellow and green all seemed to work on the white Alstroemerias. 


Why not couple this activity with actually growing some flowers with your children. The Book People have a deal on that comes with a book, terracotta pots, three packs of seeds and some wooden sticks to write on.


Follow the link below to buy it.