EXAMPLE The Effect of Caffeine on Plant Growth
2011 VIRTUAL SCIENCE FAIR ENTRY
Abstract
To explore the effect of caffein on plant growth, I planted, germinated, and grew
mung beans. I introduced caffeine into the soil of some plants and evaluated the
effects of caffeine on the experimental plants in comparison to the control plants that
were not exposed to caffeine. Results showed that caffeine help mung beans grow
faster with soil sprinkled with caffeine.
Type
Life Science, Plant Biology
Grade
Middle School, Seventh Grade
Difficulty of the Project
Medium
Cost
$10-$20
Safety Issues
No known safety issues.
Time Taken to Complete the Project
About three weeks.
Objective
The goal of this middle school science fair project is to examine the effect of caffeine on plant growth.
Materials
1 packet of mung beans
3 gardening pots
Enough soil to fill the 3 pots
Gardening utensils
Tap water
Caffeine tablets
Coffee powder
2 beakers
1 measuring cylinder
1 digital weighing scale
1 black marker
Introduction
Some plants seem to benefit and grow faster when caffeine is added to the soil, while others seem to become
stunted or grow slower. There are also some plants that are not affected by the presence of caffeine in the soil.
Caffeine can be introduced to the soil by sprinkling grounded coffee over the soil, adding leftover coffee to the
pot or watering with a caffeine solution made by dissolving a caffeine tablet in water. The grounded coffee is
actually organic matter and will help in adding nutrients to the soil. It will also attract worms that feed on the
grounded coffee and at the same time help to aerate the soil.
Hypothesis
The mung beans watered using the coffee mixture will grow the fastest.
Experimental Procedure
1. The independent variable is the solution used to water the plants – water, caffeine solution and a coffee
mixture. The dependent variable is the growth of the mug bean plants. This is determined by measuring
the height of the plants every day using a ruler. The constants (control variables) are the siz e of the pot, the
concentration of caffeine and coffee, the amount of sunlight, the temperature of the environment (which will
remain at room temperature) and the amount of water added daily.
2. Fill the 3 pots with equal amounts of soil. Plant ten mug beans in each pot and allow them to germinate.
Additional seeds can be placed in the pots in case some of the seeds do not germinate; the additional
plants can be removed later.
3. For the first 5 days, water the 3 pots with tap water only. Allow the seeds to germinate for the first 5 days.
4 . After 5 days, measure the height of the 10 plants in each pot. Add up the individual heights and divide by 10
to obtain the average height. Record the average heights in a table, as shown below.
5. Prepare the caffeine solution by dissolving 10g of caffeine tablets in 100ml of water in a beaker. Label the
beaker ‘caffeine’. Similarly, add 10g of coffee to 100ml of water in another beaker and label it ‘coffee’.
6. Label the 3 pots ‘water’, ‘caffeine’ or ‘coffee’. Over the next 10 days, water the pots once a day with 100ml
water, caffeine solution or coffee mixture, according to the labels on the pots.
7. Measure and calculate the average height of the mung bean plants every day for the next 10 days. Record
all calculations in a table.
Results
The results of the experiment were, mung beans grew faster in soil with caffeine.
Conclusion
The hypothesis that mung beans watered using a coffee mixture will grow the fastest has been proven to be
true. The effect of caffeine on plant growth is still a subject under study. Using grounded coffee in garden lawns is
a common practice to make plants grow faster. However, coffee also contains other ingredients like potassium
and phosphorous, which are known to enhance plant growth. Experiments on plant growth using only caffeine
have resulted in the plant leaves becoming wrinkled, turning brownish and exhibiting retarded growth.
Bibliography
http://www.ehow.com/about_54 74 4 20_effects-caffeine-plants.html
http://www.mycaffeineaddiction.com/the-effect-of-caffeine-on-plant-growth/
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