Companion planting has long been steeped in folklore and history, but until recently, not much research or serious study was done to determine if the practices really work. Recent scientific studies have validated some of the folklore. Many of the old sayings your grandparents passed down about planting crops together are true and could benefit your garden.
The “Three Sisters Planting” is an example of companion planting that comes from Native American practices. There is a legend about the three sisters working together. Corn, beans, and squash or pumpkins represent each of the sisters. Corn provides the means for beans to climb, while beans improve the soil for the corn and squash. The vines of the squash or pumpkins shield the soil to retain moisture and suppress weeds. It’s a wonderful picture of teamwork.
Companion planting is the practice of growing certain plants with others to create a mutually beneficial environment. The purposes for doing this are usually higher yields or pest control. This practice strives to increase the biodiversity of agricultural ecosystems. Companion planting has often been done on a small scale in home gardens but is now being implemented in increasingly larger-scale horticultural or agribusinesses.
I referred to “Companion Planting and Botanical Pesticides” as a resource, a lengthy article with loads of science-based information that you can download and take your time to read. link It also contains a companion planting chart that is based on “traditional recommendations used by gardeners…evolved from an interesting combination of historical observation, horticultural science, and a few unconventional sources.” Charts usually list plants that are incompatible as well as those that grow well together. Here are a few examples of pairings to get you started:
tomatoes with alliums (onions), carrots, basil, cucumber or nasturtium, parsley
green beans with French marigolds (Tagete patula)
crops in the cabbage family with onions
lettuce with sweet alyssum
eggplant with dill or cilantro
You may experiment with these combinations or others and keep records of your observations.
Pairing French marigolds with green beans or potatoes is a wise practice that has been handed down over the years, but new research shows that the most effective use of marigolds is to dig the spent marigold plants into the soil so that next year’s bean crop will benefit from the suppression of harmful root-knot nematodes. This tip came from Thomas G. Ford of PSU in a webinar that appeared in February 2022.
Here are some of the benefits of companion planting:
Flowers provide a nectar source for beneficial insects who thrive on aphids, flea beetles.
“Masking” odors such as onions are used to confuse cabbage moths and other pests.
Increased yields because compatible plants are more productive
Trap crops are companion plants that lure pests away from desirable plants
There are several other terms that are interchangeable with “companion planting”.
Intercropping or Interplanting is the practice of planting more than one crop together, usually on a larger scale than in a home garden. An example of this is planting cabbage in an area of white clover to suppress cabbage root maggot flies. This can be done in a “messier” fashion where there are no distinct rows or in alternating rows.
Polyculture mimics the diversity found in nature by growing multiple plants in the same space or bed. The benefit of this practice is that pests and diseases won’t spread easily, or destroy an entire crop as might happen with a single crop.
I should offer one bit of caution when you combine plants. Some vegetables don’t like competition from any other plants whether beneficial or not. One of these “antisocial” plants is asparagus. Because they are perennial and don’t like to have their roots disturbed once established, be careful planting anything in among asparagus. I have found that they do benefit from sweet alyssum, parsley, or even tomatoes but they should be grown to the asparagus bed.
Many more pairings or combinations are out there waiting for you to try. I highly recommend Jessica Walliser’s book, Plant Partners: Science-Based Companion Planting Strategies for the Vegetable Garden, which contains a wealth of science-based strategies and is easy to read.
Perhaps some of the companions are plants you already grow in your garden. Why not plant them together and reduce the need for pesticides and commercial fertilizers? You can have a lush, beautiful, and productive garden by incorporating companion planting into your habits.
As a home gardener for most of my life and a Master Gardener for 11 years, I’ve used many companion planting recommendations that I’ve shared with you. You can also visit the Idea Gardens at the Southeast Agricultural Research and Extension Center (SEAREC), 1446 Auction Road in Manheim, Lancaster County to see some of these plantings in practice during the growing season.