With the spring gardening season beginning, imaginations run wild with gardening possibilities. Some gardeners may ponder the complexities of an age-old practice that is regaining popularity in recent years – companion planting. How do certain combinations of plants benefit from being planted alongside each other, yet other combinations seem to struggle? Uncover the secrets of companion planting and unlock the full potential of the garden. Join this journey of discovery and learn the art of diversifying the garden for the benefit of all.
Explore companion planting
Companion planting is a common gardening technique that involves planting two or more plant species in proximity for mutual benefit. The practice has been used around the world for millennia to improve soil fertility, control pests and diseases, and increase crop yields. Growers of times past had no fertilizers or pesticides to help them and had to use natural solutions. For them, companion planting was one such solution.
Companion planting is commonly understood to be a diverse mix of crops, but it can include a diverse mix of varieties of one vegetable crop. According to the University of California Cooperative Extension, when researchers tested four different varieties of broccoli in close-proximity research plots that had early, mid-season, and late-season maturity dates, there were fewer aphid infestations observed overall compared to test plots with a single broccoli variety that had the same maturity dates. Diversity, even within species, strengthens collective defenses.
Three Sisters Garden
One of the most famous examples of companion planting in the garden is that of the Three Sisters Garden – the companion planting of corn, pole beans, and squash. According to the USDA, this famous combination was developed by the Haudenosaunee (Iroquois) Confederacy of the Great Lakes area and by the Cherokee Nation in the Southeast, both used it to increase soil fertility. The three sisters each supply a unique supportive role to the other two. The corn becomes a trellis for the beans to climb. The beans fix atmospheric nitrogen in the soil to fertilize the corn and squash. Finally, the squash serves as a living mulch to suppress weeds, preserve moisture, and deter pests with its prickly leaves. Together, these three crops form a symbiotic relationship that is highly productive and sustainable.
According to University of Wisconsin-Madison, the Three Sisters planting technique showed a significant (statistically significant) increase in soil drainage and higher crop yield/acre (calories/acre) while decreasing incidence of raccoon damage when compared to monoculture plantings, i.e., a field with only beans, a field with only corn, and a field with only squash. The improvements were attributed to a greater diversity in plant root architecture and less observed weed pressure.
According to Michigan State University, there are crop combinations that can increase pest infestations or disease. Examples of crop combinations to avoid are beans with garlic or onions and cabbage with tomatoes. West Virginia Extension acknowledges that companion planting is not an exact science, results vary depending on soil, geographic area, pest presence, and other factors. However, this should not deter the adventurous gardener from experimentation.
The Three Sisters technique is not only a proven and practical way to grow food by companion planting in growing spaces, but also a testament to the ingenuity and wisdom of indigenous agricultural practices. Today, this practice continues to inspire gardeners around the world to experiment with diverse and holistic approaches to food production.
ABOUT THE AUTHOR: Nick Frillman is a Local Foods and Small Farms Educator serving Livingston, McLean, and Woodford Counties. A fourth-generation graduate from University of Illinois, Frillman has a B.A. with a double major of Political Science and Spanish and a M.S. in Crop Science with a focus on crop production. Before joining Illinois Extension, Frillman completed a field season of CSA and farmers’ market-style production at a small “beyond-organic” vegetable farm in Sandy, Oregon.
ABOUT THE EDITOR: Liz Repplinger is the Agriculture and Natural Resources Program Coordinator serving Livingston, McLean, and Woodford Counties. A Bloomington-Normal native, Liz earned a B. A. in Animal Science and an M.S. in Animal Science from Illinois State University. She has enjoyed contributing to the multiple facets of Extension including previous support of the 4-H Youth Development Program as a program coordinator and current support of Unit and Statewide Diversity, Equity and Inclusion Initiatives.