Benefits of Companion Planting

Medically Reviewed by Jabeen Begum, MD on November 25, 2022
Written by Julian Selemin
4 min read

Companion planting is the practice of enhancing your crop production by growing combinations of different plants close together. Some combinations can significantly benefit plants and enrich the soil, while others can negatively affect crops. 

Companion planting is a gardening technique consisting of planting different crops together to improve their health and productivity. Companion planting has many benefits. It optimizes productivity in gardens with limited space and can help prevent pest infestations and disease.

One of the most exciting aspects of companion planting is that different combinations of plants can have various benefits, so the technique is ideal for gardeners who enjoy experimentation.

Companion planting can be more complex than it sounds. Not every combination works, and some species can have a negative impact on others. Walnuts, for instance, secrete a poisonous chemical that can damage most other crops, and potatoes are best grown away from eggplants and other nightshades because they will compete for nutrients.

While the benefits of companion planting vary depending on the crops selected, certain benefits are common to most plant groupings, such as:

Increased yields. The main benefit of companion planting is its ability to maximize crop yields. The exact mechanism behind this varies according to the different plant combinations. Cornstalks, for instance, provide a living trellis that beans can climb and thrive on without needing an artificial structure or trellis.

Maximizing space. One of the few companion planting benefits shared by most plant species is maximizing garden space. Because the technique allows you to plant several species close together, it frees up space previously waste.

Soil health. Certain plants can improve the nutrient quality of the soil. Beans, peas, and clover are some of the most popular choices because they add nitrogen to the soil. Other species, such as carrots and radishes, can help prevent the soil from getting too compacted.

Repelling pests and weeds. Some plants can act as a repellent for both pests and weeds. Dill, for instance, attracts predators that feed on pests. Marigold releases a chemical that repels root-eating nematodes. Certain plants can slow the growth of weeds, which can help keep them in check.

Many crops can be used for companion planting. But each plant will interact differently with the other species present on that plot of land, so it is important to research combinations before starting.  Some examples of crops that work well together include:

Pole beans, corn, and winter squash. This combination of vegetable garden crops works so well it has earned its own popular name: “the three sisters.” The winter squash protects the soil from weeds and helps it stay moist with its broad, low-growing leaves. At the same time, the corn acts as a trellis for the pole beans to climb. 

Cabbages and aromatic herbs. Cabbages attract worms and other pests that can ruin crops. Aromatic herbs, such as basil and rosemary, can help repel some of these species. While tomatoes are sometimes planted near cabbages to repel moths, this pairing is not ideal because these two species will compete for nutrients.

Cucumbers, radishes, and sunflowers. Planting cucumbers and radishes together improves their growth and productivity. Planting sunflowers near cucumbers provides shade to the cucumbers. 

Tomatoes, marigolds, and basil. Most aromatic herbs are suitable for companion planting with tomatoes. Basil, for instance, can improve the growth and flavor of your tomatoes, while planting marigolds on the same plot will help repel pests and worms.

Some combinations can have bad interactions and harm your crops. Still, the interactions will change depending on where you live and other variables. Some examples of common bad companions to avoid include:

Potatoes and tomatoes. Plants in the same family often compete for the same nutrients in the soil.

Strawberries and members of the cabbage family. Strawberries impair the growth of cabbages and broccoli, cauliflower, collard greens, and more.

Onions and beans. Because onions and beans require different growing conditions, planting them in proximity can mean that onions will hinder the beans’ growth.

Cucumbers and aromatic herbs. This pairing doesn’t work well because some herbs can stunt cucumber growth. Cukes have a delicate flavor, and strong herbs grown in the same soil can change how they taste.

If you are still determining whether a combination will work, try planting them in small quantities and keep a close eye on them. If you notice that your plants aren’t growing as quickly as they should, they are probably bad companions and shouldn’t be planted close together.

Due to the variety of combinations and their effects, no companion planting guidance applies to every set of crops. But you can follow a basic guideline.

First, consider which crops to use for companion planting. Check companion planting charts for this, as they will give you an idea of which plants work well together. The ideal combination optimizes your crops’ productivity, repels pests and weeds, and grows well in your climate.

Different combinations require different spacing, but a good rule of thumb is to space them so that their leaves will barely touch each other when they’re fully grown.

Keep a close eye on your crops once they are on the ground, and watch the interactions among the different species. It's also a good idea to keep a journal to keep track of the pros and cons of each combination.