Plants Suck: Observing Natural Capillary Action

How do flowers get water up from the ground or a vase and into their stems, leaves, and petals? Use food coloring to demystify this gravity-defying feat of nature, and watch as a white flower changes color before your eyes!

Your child will learn about the forces that can move liquids, including gravity and suction, about how plants are able to nourish themselves with clever mechanics, and about colors and color mixing. He'll also end up with a unique custom-dyed flower!

What You Need:

• Water
• One or two clear jars or plastic containers
• White carnations
• Food coloring

What You Do:

1. Fill a clear jar about halfway with water.
2. Ask your child to choose a color. Add quite a lot of food coloring to the water jar. Your child can help with this if he wants to, but watch out for his clothes!
3. Cut off several inches from the bottom of the stem of a white carnation and then ask your child to put it in the jar.
4. Observe it every day to see if the food coloring can be seen in the petals.
5. If you want to get fancy, use two jars and two colors, and split the carnation stem between the two jars of colored water. What happens to the petals?

What You Talk About:

• How did the color get into the stem/leaves/flower? Did it have to go up or down to get to the petals?
• Does water usually move up or down?
• Explain to your child: The important thing about capillarity is that it can make water move up. This is opposite the direction water usually moves, which is down due to gravity. The tiny pieces of water that can get into tiny tubes in the flower are small enough to be drawn upwards by being attracted to the sides of the tubes or capillaries in the stem. The attraction is stronger than the pull of gravity.

Try making more flowers of different colors! They make great gifts and give your child a lovely opportunity to show off his newfound scientific knowledge.