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Weed control using Bay laurel leavesFeatured science projectScience project video


The materials required for this science fair project:
- 5 pots of weeds
- 1 kg of Bay laurel leaves
- 1 juice extractor
- 1 measuring cylinder
- 5 spray bottles
- tap water
- 1 black marker pen


1. For this science project, the independent variable is the concentration of the juices from the Bay laurel leaves – 25%, 50%, 75% and 100%. The dependent variable is the time taken for the weeds to change color and the weeds to become dry and dead. This is determined by observing the weeds every day. The constants (control variables) are the size of the pot and the amount of Bay laurel leaf juice used.

2. The 5 pots of weed and the 5 spray bottles are labeled as 0%, 25%, 50%, 75% and 100%.

3. The 1 kg of Bay laurel leaves are placed inside the juice extractor with some water added to help extract the juice. The extracted juice is mixed with tap water at the following ratios and poured into the marked spray bottles:

a. Spray bottle marked 0% - only 200ml tap water used

b. Spray bottle marked 25% - 50ml Bay laurel juice with 150ml tap water

c. Spray bottle marked 50% - 100ml Bay laurel juice with 100ml tap water

d. Spray bottle marked 75% - 150ml Bay laurel juice with 50ml tap water

e. Spray bottle marked 100% - 200ml Bay laurel juice

4. For the next 12 days, the mixed solution in the spray bottles is sprayed over the weeds in the pot. The marking on the pots containing the weeds must be the same as the marking on the spray bottles.

5. The conditions of the weeds are observed everyday for the next 12 days. Observations are made on the color changes in the weeds in order to verify if the weeds are alive or dead. The observations are recorded in the table given below.

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Complexity level:
Project cost ($):
Time required:
2 hours to prepare, 12 days for science fair project
Material availability:
May be purchased from a plant nursery
Safety concerns:

Handle chemicals with care and dispose of them properly. Wear safety gloves and goggles to prevent injury