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Botany Science Fair Project

Planting Companions

Planting Companions | Science Fair Projects | STEM Projects
Have you ever wondered if planting different types of plants together can help them grow better? This science project will explore the idea of companion planting and see if it can help plants grow faster and produce better crops.


The hypothesis is that some plants will interact well with one another and increase in their rate of growth whereas other plants may not get along well together and growth will be delayed.

Method & Materials

You will plant different types of plants in 5 pots, measure the growth rate of the plants, and calculate the average height.
You will need 1 packet of tomato seeds, 1 packet of corn seeds, 6 onions, 5 plastic pots, enough soil to fill the 5 pots, and a ruler.


The experiment showed that tomato plants grow well with onions but not with corn. The tomato plant grew an average of 48mm by itself in pot A but was able to grow up to 65mm when planted with the onion in pot D. However the tomato planted in pot E together with the corn, was only able to grow 28mm in the 10 days.

Why do this project?

This science project is interesting because it explores the idea of companion planting and how it can help reduce the use of chemical pesticides to protect the plants.

Also Consider

To further explore this project, consider repeating the experiment using different plants like radish, potato and peas. Also, consider continuing the experiment over a longer period.

Full project details

You can find additional information and details for this science fair project here. Have fun exploring!

Related video

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