Companion Plants, Biodiversity, & Bugs

Think of how many different kinds of plants grow in a forest or any uncultivated area. These environments contain a large variety of plants, animals, and insects. Plants thrive in biodiversity. A variety of plants supports a variety of creatures in the garden and microorganisms in the soil, each providing different services to the garden ecosystem. By thinking of your garden as an extension of the larger ecosystem around us, you can provide services to wildlife and benefit from their presence with greater yields from less work.

Biodiversity in a vegetable garden means not just planting different types of vegetables, but growing other types of plants as well, such as flowers and grains. Native flowers, grasses, and perennials help attract helpful native insects, and provide a stability that is usually lacking in a vegetable garden as we change crops, till soil, and pull up plants. In choosing plants for your garden to provide biodiversity, consider what the garden creatures will need, and the services they and different plants will provide to the vegetables, which are the main crop. Plants which provide services to your garden are sometimes called companion plants.

Garden creatures need food such as nectar and pollen and they need habitat to overwinter and raise their young. We want to encourage earthworms, predatory toads, ground beetles, spiders, birds, and snakes to help create a balance in the garden. These garden predators and the many beneficial insects we want need a water supply and some place protected to thrive. A water feature, logs and brush piles, and groups of rocks are all things that support garden helpers. Companion plants can help provide food and habitat.

There are many companion planting charts available which give a variety of advice about what plants grow best together in your garden, but many of them don’t apply to our area because they suggest pairing plants which don’t grow in the same season for us. Also there is a lack of scientific evidence to support many of those claims. Companion plants actually are a much broader category than just planting two vegetables together which supposedly increase their yields.

Companion plants can attract beneficial insects, such as pollinators or predators, and repel certain pests. They can provide nitrogen for themselves, other crops around them, and crops that follow them. Some companion plants can mine minerals from deep in the soil and return them to the top layers of soil for use by other plants. Some attract bad bugs away from your crops. They can provide weed control, regulate sun exposure on adjoining plants, and provide natural trellises. They can add biomass to improve the texture of your soil and provide nutrition for your plants. They can provide living mulch. Different companion plants will provide different services to the garden.

In the VegHeadz demonstration garden, increased pest pressure has caused us to reconsider traditional garden rows and monocultures. Consider a different style of gardening to control pests and avoid the use of pesticides. Planting different species together, including selected non-edible plants in beds or groups rather than rows of the same plant, provides many benefits. Companion plants should be intermingled with vegetables to provide the best results, not just parked at the end of a row. 

Planting companions for your vegetable crops work best when you make note of what works in your garden from season to season. The interaction of plants with each other and with the other denizens of the garden is complex, and each garden environment is different.

For more information and ideas about specific companion plants and their benefits search “Companion Plants IFAS.” Another good reference is “Plant Partners—Science Based Companion Planting Strategies for the Vegetable Garden,” by Jessica Walliser, Storey Publishing, 2020.