Do Insecticides Stunt Plant Growth

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Author: Sofia PC

Grade Level: 6th - 9th;  Type: Botany


In this experiment, we will find out whether insecticides stunt plant growth or make no difference.

Research Questions:

Are insecticides harmful to humans?

Plants grow through a process called photosynthesis. This requires sunlight to take place. The chlorophyll located in the chloroplast of the plant cells grabs sunlight and starts the reactions (such as sugar) that are needed to make the plant grow. Water is also needed in the growth equation, because like humans and animals, plants need moisture to quench their thirst.

Insecticides repel bugs-bugs is not a good thing for plants (except for pollinating insects) as some of these insects drill holes and contaminate the plants.


  • Any insecticide (don't need a huge bottle)
  • bean seeds
  • soil on the ground
  • water
  • sunlight

Experimental Procedure:

  1. Plant 2 groups of seeds at a distance from each other in an outside yard. Make sure however, that they will get the same amount of sunlight.
  2. Spray some insecticide on one group of seeds. Remember which one!
  3. Observe the germination rate and growth of both of the seed groups.
  4. Every few days, spray the designated plant with insecticide.
  5. Record any difference you see in overall plant health and growth for several weeks-1 month.

Suggested Chart


Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
With Insecticide








No Insecticide









Terms/Concepts: Insecticide; Plant Growth; Photosynthesis


Greene, Stanley A.; Pohanish, Richard P. (editors) (2005). Sittig's Handbook of Pesticides and Agricultural Chemicals. SciTech Publishing, Inc. ISBN 0-8155-1516-2.

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