Like many things in life, the best results are achieved by working together. This is especially true with plants!
Although you may have heard about plants that are thought to aid in insect control, disease prevention or the benefits of pairing particular plants in certain areas, the latest research on “companion planting” goes far beyond random recommendations or traditional lore. The latest research reveals the need to look at our gardens in a more holistic way: as ecosystems where plants interact with each other to create a healthy, bio-diverse place. Key to understanding this concept is that plants actively affect each other. They do this through fungal associations, chemical messaging and allelopathy, which is the ability of one plant's chemistry to affect the growth and development of another. They also share resources, attract pest predators, and improve each other's nutrient availability and absorption.
When we plant one type of plant in an area, whether it's tomatoes or other vegetables, we create what is known as a “monoculture.” Although it makes large scale farming possible, monoculture leads to increased reliance on pesticides and chemical fertilizers. However, when we choose different plants to grow together, we create a “polyculture,” which leads to biodiversity. Why is this important? Biodiversity means a more stable environment for veggies and other plants to thrive by enhancing nutrient cycling, water conservation, fewer pests and ultimately, more carbon sequestration.
What is modern research-based companion planting? Scientists prefer terms like inter-cropping or inter-planting to describe creating a polyculture to achieve desired benefits in the garden. Using a scientific approach helps us to understand the why and how of successful planting combinations.
Jessica Walliser, author of “Plant Partners: Science-Based Companion Planting Strategies for the Vegetable Garden,” provides plant partnerships that have undergone scientific scrutiny and shares plant pairings that help to reduce pests, minimize disease, support pollination and improve soil fertility. Walliser's findings are the basis of this article.
Using science as your guide, gardening with companion plants will help you learn about your own unique corner of the world. Have fun as you experiment with plant combinations and create a bio-diverse habitat outside your door. You'll look at your garden in a whole new way as you observe the changes in color and texture--all the while appreciating the overall health in your garden.
Cynthia Nations is a UC Master Gardener who is currently learning and employing companion partnerships in her garden in El Granada. The article was co-authored and edited by Maggie Mah, a UC Master Gardener, who is trying to catch up with Cynthia Nations.