Question: When you put a flower in colouring the petals change colour. Could that mean you can change the colour of grass?

Thomas Perriment answered on 21 Jun 2018:

Haha what a brilliant idea! Love it. It’d be so funny to come home to blue or pink grass! So you can dye flower petals because the dye goes directly through the stem into the petals, which is how you can get multicoloured flowers that were originally white! With grass it’s a little different, as you can “top-up” the green of it by adding food colouring to the water and soil (this is actually quite common!), however I think you’d struggle to get rid of the green and replace it with another colour. Grass is green because the chlorophyll in the grass absorbs most visible light except for green wavelengths which it reflects instead. It’s hard to overcome this! Flowers require more water, so more dye gets into the system than with grass. Ask your teacher/parent/guardian if you can conduct an experiment with blue or red food colouring if you want to see for yourself!