Here’s a fun way to make flowers ANY colour that you want! They make a great gift for birthdays and holidays like Mother’s Day.

Flower with coloured petals half blue and half red, stem in blue and red liquid.

You will need

  • Flowers with white petals (white carnations or chrysanthemums work best)
  • Food colouring (1 or more colours)
  • 1-4 cups
  • Spoon
  • Water
  • Paring knife


This activity involves using a small knife to cut flower stems. Ask an adult for help with these steps.

What to do: classic 1-colour flowers

  1. Fill a cup about 3/4 full with water.

    Filling a glass with water from the tap.
  2. Add about 10 drops of food colouring in a colour of your choice and stir with your spoon.

    Glass of green liquid.
  3. Add the flowers to your cup, stem first. If needed, use a knife to cut the stems so that the flowers fit in your cup. Ask an adult to help you with this step.

    White flowers with stems in a glass of green liquid.
  4. Wait 2-3 days. It will take this long for the flowers to completely change colour but keep checking on them to see how the colour spreads throughout the petals.

    White flowers with red dyed petals.

What to do: multi-coloured flowers

  1. Gather 2 cups of the same size and fill each one with water to about 3/4 full.

  2. Add 10 drops of food colouring to each cup, using a different colour in each cup. Stir each cup with a spoon.

    Two glasses of coloured liquid.
  3. Cut off the stems of the flowers so they fit in the cups.

  4. Cut the bottom part of the stem lengthwise into two halves and put each half into a different cup. Ask an adult to help you with this step.

    Cut stems lengthways.
  5. You can make your flowers be almost as many different colours as you like. All you need is enough cups of water with food colouring, and you need to be able to keep cutting the stem without it becoming too small.

    Flower stems in two different glasses of coloured liquid.
  6. Wait 2-3 days for the colour to spread throughout the petals.

    White flowers with red and blue coloured petals.

What’s happening?

Flowers drink water through their roots, which travels up the stem into the petals. Even without the roots, a flower can still drink through its stem. One of the main reasons water can travel up the stem is a process called capillary action.

Capillary action happens in narrow tubes which could be made of glass, plastic, or in this case, the tiny pipe-like cells inside the flower’s stem. Each pipe-like cell is only a few microns (one one-thousandth of a millimetre) in diameter – very narrow! Capillary action works because the water molecules are more attracted to the wall of the narrow tube than to the other water molecules around them. This allows the water to climb up the walls of the tube and seemingly defy gravity.

Capillary action is one important reason why the water travels from the cup to the petals, but how do the flowers change colour? As the water travels up the stem to the petals, the water takes the food colouring with it. Once the water gets to the petals, it evaporates, leaving the food colouring behind in the petal. This is what changes the colour of the petals, creating a beautiful gift or just something nice to look at.

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