Skip Navigation

Biological Energy - Growing Plants

You are going to have the chance to use the scientific method and experiment with how you can use light as a variable to determine its effect on the growth of plant seeds. Make sure that you use clear containers so that you can observe the seeds germinating. Remember to control all other variables so you are only testing the effect of light!

Materials:

  • Seeds - any kind - wheat seeds from a health food store usually germinate in a day or two
  • Potting soil
  • Two empty 35mm. film canisters
  • Metric ruler
  • Water
  • Pipets
  • Aluminum foil
  • Paper towel or cotton cloth

Procedure:

  1. Begin by creating a small hole (<6mm) in the center of the canister. You may carefully heat a nail over a Bunsen burner. Other options include using a soldering iron or a drill.
  2. Always begin a planting cycle on a Monday or a Tuesday. This allows at least three consecutive school days for observations.
  3. Moisten the potting soil until it is slightly damp.
  4. Insert a wick of paper towel or small piece of cotton cloth through the small hole in the bottom of the canister.
  5. Fill the film canister half-full with potting soil.
  6. Put four seeds around the perimeter of the film canister. You should be able to see the seed from the outside.
  7. Add more potting soil until the film canister is three-fourths full. Do not pack the soil.
  8. Tear off two pieces of aluminum foil.
  9. Fold the edges of each piece of aluminum foil to form a "tray" to put under your canister.
  10. Put one film canister in a well-lit place (such as a window ledge) and the second film canister in a dark place (such as inside a cabinet.)
  11. If the soil feels dry add water with a pipet or eyedropper. Once the plant germinates, be careful not to over water it.
  12. Take observations each day for about two weeks. Your observations could include days until germination, plant or leaf color, presence of mold, shape of plant or leaf, etc.
  13. When your plants are tall enough, measure each plant in centimeters and take an average for each of your two test locations.
  14. Record the data in a table similar to the one below:
      Seeds in the dark Seeds in the light
    Monday    
    Tuesday    
    Wednesday    
    Thursday    
    Friday    
    Monday    
    Tuesday    
    Wednesday    
    Thursday    
    Friday    
  15. Use the data to create a line graph to compare the variable of light on seed germination and plant growth.

Extensions: Do a similar experiment using different variables such as fertilizer versus water, sand versus potting soil, or another variable you get permission from an adult to use.

Safety concerns: Be sure to follow all chemical safety rules that are specified by your teacher in all general laboratory experiences. As with all science lab activities, the most important safety rule is to follow all teacher directions.

Analysis:

  1. At which location did the seed germinate first?
    • Was this what you expected?
    • Why or why not?
  2. At which location were the tallest plants produced?
  3. Is light a necessary factor for seed germination?
    • Defend your answer using the data from your experiment.
  4. How is light a factor for plant growth?
utah state board of education This Sci-ber Text was developed by the Utah State Board of Education and Utah educators.