Science projects with changing flower colors

Written by karen adams
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Science projects with changing flower colors
Scientists study the ways flowers change colours in greenhouses. (Jupiterimages/Creatas/Getty Images)

Ever see a purple and yellow rose? How do florists change the colours of their flowers? Flowers easily change colours depending on their water supply. Science projects show how flowers change colours as well as answer important questions about how water moves through plants and what dyes do to the flower's colouration.

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For science projects with changing flower colours, you need white carnation flowers, slender glass vases, food colouring in red, yellow, blue and green, a knife and water. Kids do need help from an adult during this experiment. The glass cups or vases are important so you can see the colours being fed to the flowers, but you can also use plastic cups. You will need 24 hours of observation for this experiment.

The Experiments

Begin by filling each cup halfway with water. Then add 20 to 30 drops of food colouring to each cup. Trim the stem of the flowers at an angle for a fresh cut (an adult needs to handle the knife). Place some of the cut flowers in cups of coloured water, reserving a couple for the second experiment.

For the second experiment, slit the stems of the remaining flowers straight up the middle, but stopping a few inches below the flower head. Place two glasses, with different coloured food dyes in each, next to each other. Gently separate the slit stems, placing one side in one glass, and the other in the different glass.

Hypothesis and Questions

Develop some predictions and a hypothesis about the science project. Ask questions about what happens in the experiment. How long does it take for the colours to soak into the petals? Do any colours show up faster than others? Will split stem flowers absorb the same way as regular stem flowers? For the split stem experiment, which side of the flower will one glass's water migrate to? You should check the flowers every few hours in order to answer these questions.

Observation and Conclusion

As the water travels up the stems, you notice the petals changing colours according to the food colouring in their drinking supply. This is a process called "transpiration." Plants suck up water through tubes called "xylem," which are veinlike structures in the stems and leaves. When observing how the dye moves through the flowers, you might notice that blue dye moves through the plant the fastest, followed by red and green dyes.

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