Experiment 4

Are small amounts of soap or detergent harmful to the growth of plants?

Materials:

  • Radish or beet seeds
  • Soap and detergent
  • 3 Styrofoam cups
  • Soil
  • Water
  • 2 Quart jars

Do this first:

This is a picture of sproutsFill the jars to the same levels with water, and then make soap and detergent solutions. For one jar use 1/4 teaspoon detergent and fill with water. For the other, use 1/4 teaspoon soap and fill with water.

1.Plant 2 seeds in each cup, about 1-cm deep, and place in a sunny windowsill.

2. Water one cup with 2 tablespoons of soap solution every day.

3. Water a second cup with 2 tablespoons of detergent solution every day.

4. Water the remaining cup with 2 tablespoons of tap water every day.

5. Chart the growth of plants in each cup. Compare the results. Which sprouts first? Which grows fastest?

OTHER IDEAS TO EXPLORE:

What happens to soap when it leaves your bathtub?