Companion Planting

by Dana Kester-McCabe

Carrie Murphy, with the Delaware University Cooperative Extension, tells us about companion planting.

Companion planting is an ancient practice that is being rediscovered and studied. I recently spoke to Carrie Murphy, Extension Educator in Horticulture with the Delaware University Cooperative Extension, about companion planting today.

Carrie Murphy:
"There's a little bit of literature and a little bit of research that's been done to support the idea of companion planting. Many vegetable gardeners that have been vegetable gardening for a long time, they swear by it. It's the idea of planting two or more plants together that are companions to one another. So they like to grow together; and in fact, have been noted to enhance production.

"For example, a lot of people like to put tomato plants with basil. And, some gardeners will tell you that enhances the flavor of the tomatoes. Some gardeners will tell you that the plants that they use as companions to the vegetables will attract pollinators and beneficial insects that will, again, enhance the growth of that tomato."

"Commonly planted vegetables like carrots, cucumber, eggplant, they have suggested companion plants. And on the flip side there are some plants that have been noted to not grow well together."

"I think ultimately what vegetable or food gardeners want to see is better production. And so I think that's always a goal. How can you grow plants together so that your get a better tasting plant, a better healthier plant, a better producing plant. And, you know, the more tomatoes you can harvest, the better tasting tomatoes that you can have, I think is really what people are striving for."

"There are a number of extension publications that you can download from the internet that focus on companion planting and provide charts where you can look up what you are growing and then see what grows well with it. And it has to do with the conditions in which they are being grown. And, it also has to do with the way the plants grow. So, whether they are vining or bushy, and maybe they are low growing or tall growing; so it has to do with that as well. Often times too it is the idea of attracting pollinators and beneficials."

"Something we have done here at the Extension Office is our master gardener volunteers have designed and installed a vegetable garden at our office which serves as a teaching garden. And, together with our integrated pest management specialist Dr. Brian Kunkle, we've designed the space so that we actually have a perimeter planting around the garden of a number of native plants that we know will bring in pollinators and beneficial insects. That will then target some insect pest that will show up in your garden. A common example is aphids on your plants and lady beetles like to eat aphids. And so we've tried to identify some native plants that really attract a diversity of beneficial insects that will target some of the insect pests that show up in our garden."

Carrie says some varieties of flowers mixed in with the fruits and vegetables are also helpful warding off some troublesome critters.

Carrie Murphy:
"Marigolds are one example. More than anything it has to do with the fragrance of the flowers of the leaves which has been noted to repel some insect pests and some small mammal pests. So, that is one that people like to plant in particular around the edges of their garden. Or if you are gardening in a raised bed, put them in the corners. A lot of people like to tuck herbs in."

"Flowers that you can eat are fun too. Not only are they sometimes attracting beneficial insects, but things like pansies and nasturtium. Be thinking about what you can get out of your garden, and what you can harvest: everything from roots to stems, to leaves and flowers."

"We try to encourage diversity and not planting, for example one stand of tomatoes. We like people to interplant and diversify their plantings. Just because, if one tomato gets sick, it can then spread to the other tomatoes. So if you can really diversify the planting it can help you to manage certain diseases and problems that can surface in your garden."

The cooperative extension offices in each state have diagnostic services that you can contact to help you identify diseases and which insects in your garden are pests and which are beneficial.

Companion planting is not only a good gardening strategy. According to Carrie it makes for a much more interesting landscape.

Carrie Murphy:
"I really tuck my vegetables and my fruits among my ornamentals. It is a really blended way of gardening. In every open space between my ornamentals I tuck greens and cucumbers and herbs and whatever it is that I want to grow that particular season. You really can walk around my entire yard and find something to eat. That was one of my goals. I just continue to have fun with that."

Find out more:
Delaware Cooperative Extension Home Garden Section
Wikipedia Companion Plant List
Wikipedia List of Edible Flowers
Native American Companion Planting: The Three Sisters