PLSCI 20L Help Another, Help Yourself

1. Help Another, Help Yourself:
Companion Planting
By: Brayan Cano and Johanna Fisher

2. What is Companion Planting?
● Companion planting is the practice of interplanting
different species of plants to enhance each other’s
growth or protect each other from pests.
● Such examples of enhancement are increased crop
productivity and attracting beneficial insects.

3. Plants for Experimental Companion Planting
● The plants chosen for this experiment are marigolds
and radishes.
● Marigolds exhibit repellent properties towards pests
and radishes have a fast growth period with less than
30 days.

4. Purpose
● The purpose for this experiment is to test the effects of
companion planting on marigolds and radishes and see
how beneficial they are.
● It’s also to determine the nature of symbiosis between
these two plants.

5. Locations
● The entirety of the experiment was conducted inside
the Woodland Community College Greenhouse.
● The greenhouse provided consistent irrigation,
sunlight, and temperature and prevented any external
factors that would complicate the data.

6. Methods
● Companion radishes and marigolds matured at 5cm
and 12cm spacing, respectively.
● Grown in 1 gallon nursery pots.
● Separate radish (3) and marigold (3) control groups
grown in same conditions for comparison to the
companion group.

7. Methods Cont.
● Data was gathered at weekly interval by measurement
of apical height.
● Radishes were extracted at week 4 and weighed
● A double-blind test trial was conducted to compare
palatability of the two groups

8. Growth Rate Comparison

9. Average Extraction Mass per Radish

10. Results
● Our hypothesis was that the growth rate, pest hardiness,
and flavor would be improved among radishes planted in
proximity to marigolds.
● Data shows that, despite the theory, the control group fared
better than the companion group in growth rate. Pest
hardiness was not a factor during testing.

11. Results Continued
● The taste trial revealed testers detected less spiciness in 77%
of the companion radishes, indicating appeal to general
market preference towards mild flavor.
● Results may be refined with initial transplant [instead of
direct seeding] of marigold and subsequent direct seeding of
radish, in order to observe companion effect of marigold
bloom on radish development.

12. References
Schalau, Jeff. “Marigolds and Nematode Management.” Backyard Gardener, Arizona Cooperative Extension,
Yavapai County, June 2004,
https://cals.arizona.edu/yavapai/anr/hort/byg/archive/marigoldsandnematodemanagement.html 24 March 2022.
Philbrick, Helen and Richard B. Gregg. Companion Plants and How to Use Them. Biodynamic
Farming & Gardening Association. © 1966, 2008. 25 March 2022.
Conboy NJA, McDaniel T, Ormerod A, George D, Gatehouse AMR, Wharton E, et al. “Companion
planting with French marigolds protects tomato plants from glasshouse whiteflies through the emission of airborne
limonene.” PLOS ONE, March 1, 2019, https://doi.org/10.1371/journal.pone.0213071. 25 March 2022.
Burpee Organics. “French Breakfast Radish.” Seed Packet, Burpee Garden Products Co. 2021. 24
March 2022.
Ferry~Morse. “Marigold Dwarf Bolero.” Seed Packet, Green Garden Products, Ferry-Morse Gardening
2022. 24 March 2022.