Basil companion plants: The best garden partners for basil plants

Basil (Ocimum basilicum) is an annual herb that not only brings flavor to the kitchen, but also surprising benefits to the garden. There are dozens of varieties of basil, and they all make great companions for so many other edible plants. This article isn’t focused on increasing your basil yield or even on how to make your harvest. Instead, it’s about which basil companion plants are great choices to grow side-by-side in the garden.

What is companion planting?

Companion planting is an age-old technique that partners two or more plants together with the goal of providing specific benefits for one or more of those plants. Those benefits could be reducing pest pressure, improving yields, enhancing disease suppression, or another targeted positive outcome.

Unfortunately, some companion planting methods are based on folklore, rather than on sound science. But there is also some surprising university research that has examined companion planting with interesting results. In previous articles, I’ve introduced research-proven tomato companion plants, great zucchini companions, and even the best companion plant partners for peppers. Today, let’s dive into basil companion plants and how to use them in your garden.

Why is basil a great companion plant?

Yes, basil leaves are known for their unique taste and for the way they enhance the flavor of soups, sauces, and many other dishes. The leaves also contain many nutrients. But their culinary potential is not the only reason to grow this herb. Basil also makes a great companion plant for so many other veggies and herbs.

The primary advantages provided by basil in the garden are as a deterrent for certain pests, as a draw for beneficial predatory insects, and as a pollinator magnet to help improve pollination rates of certain nearby crops. In the sections that follow, I’ll introduce some very specific basil companion plants to try in your garden and let you know why they may be effective in your plot.

Basil gives more than it gets

Including basil in vegetable gardens, raised beds, and even in containers is an all-around good idea, even if you don’t eat the plant (but why wouldn’t you!). Basil makes such a good companion plant because it’s the best kind of partner – a giver! It brings numerous benefits to the garden while requiring very little in return. As a companion plant, basil is often the provider in the relationship, rather than the beneficiary. The basil is the one that brings the benefits to the table. Let’s talk next about what some of those benefits might be.

What basil can do for your garden

As mentioned, the three primary benefits of using basil as a companion plant are:

1. Improved pollination. When basil flowers, the tiny blooms are visited by many different species of native bees and flies, many of which are also pollinators of common fruit and vegetable crops. The presence of basil flowers in your garden means more nectar is available to these pollinators. This often results in higher populations of pollinators and improved pollination rates.
2. Improved biological control. Those same tiny flowers also provide nectar for various species of predatory beneficial insects (aka good bugs that eat bad bugs). Ladybugs, lacewings, parasitic wasps, hoverflies/syrphid flies, and other beneficial insects enjoy basil nectar. And while they’re in the garden, they’ll also consume and control many common pests, such as aphids, caterpillars, the larvae of certain beetles, thrips, and many more.
3. Improved pest control. Though there is a lot of folklore around basil as a pest deterrent (some people say it deters all pests, which is certainly not the case), there have been some studies that have shown basil to be a helpful deterrent for certain pests in the vegetable garden.

In the sections below, I’ll introduce some basil companion plants that have been shown to receive one or more of these benefits when basil is grown nearby.

The best basil companion plants

Below, you’ll find the plants and plant groups that make the best basil companion plants, according to research. If you want to learn more about science-based companion planting techniques for everything from healthier cucumbers to fewer asparagus beetles, I encourage you to pick up a copy of my book Plant Partners: Science-Based Companion Planting Strategies for the Vegetable Garden (Storey Publishing, 2020).

Tomatoes: the essential basil companion plants

Yes, the rumors are true! Tomatoes do make great garden partners for basil. Not only are these two edibles successful together on a plate, they are also a match made in heaven in the garden. The main benefactor of the partnership is the tomato plant, but of course the gardener benefits as well. The value basil provides to tomato plants is in the form of pest control. Basil helps deter three main pests from tomato plants:

1. Thrips. These tiny narrow insects cause stunted new growth and fruits that are distorted and speckled with silver puckers. Both western flower thrips and onion thrips feed on tomato plants (which is why you should not grow onions near tomatoes if you have a thrips problem). The presence of tall basil plants next to tomatoes was shown to reduce damage from thrips
2. Yellow-striped armyworm. One study showed a reduction in the egg-laying behaviors of these leaf- and fruit-eating pests on tomato plants when basil companion plants were growing nearby. Surround tomato plants with basil to deter this pest. Yellow-striped armyworms are common in the southeastern and eastern US, as far west as the Rockies.
3. Tomato and tobacco hornworms. Planting basil with tomatoes has been shown to limit egg-laying behaviors by adult hornworm moths. Hornworm caterpillars can be difficult to spot on tomato plants, especially when they are small. Tall varieties of basil planted between and around tomato plants resulted in reduce egg-laying and therefor fewer hornworms and less damage.

Eggplants: another excellent partner for basil

Just as it was for tomatoes, the presence of basil companion plants near eggplants was shown to reduce damage from thrips. And since eggplants are also susceptible to damage from tomato and tobacco hornworms, interplanting them with basil can help reduce the numbers of these pests, too. Interestingly, the same holds true for peppers.

Cole crops: surprising basil companion plants

Cole crops such as kale, cabbage, broccoli, cauliflower, and collards, also receive surprising benefits from having basil as a neighbor. Here’s how this plant partnership works.

1. Slugs and snails really enjoy basil, even more than they enjoy cole crops. If you find your cabbage or broccoli plants are falling victim to these slimy pests, interplant them with basil. Yes, in this situation the basil will be a sacrificial crop, rather than a harvestable one. Essentially, you’ll be using the basil as a trap crop to lure the slugs and snails from your brassicas.
2. Imported cabbageworms relish cole crops. The adult butterflies readily lay eggs on their leaves, and the resulting little green caterpillars can decimate the plants in short order. Interplanting cole crops with basil companion plants helps manage the cabbageworm population in two ways.
   • First, the volatile chemicals (scents) released by the basil leaves may help mask the presence of the cole crops, making it harder for the adult cabbageworms to find their favorite egg-laying sites and thereby reducing the damage they cause. Interplant basil with cole crops or have them in very close proximity of each other.
   • Second, the flowers of basil draw in pollinators that are also common predators of cabbageworms (primarily parasitic wasps). The more of these good bugs you have around, the fewer cabbageworms. Flowering cilantro is another good plant to have in your garden for this purpose.

Lettuce: a great companion plant for basil

Basil plants make good partners for lettuce because of the enhanced biological control they encourage. Aphids are very common lettuce pests, and two of the beneficial insects that enjoy preying on them the most are hoverflies/syrphid flies and parasitic wasps. And guess what these two predators like to drink? You guessed it! The nectar of basil flowers. Other good herbs to let flower in your garden for the same purpose are oregano, fennel, and sage. Sweet alyssum is another favorite companion plant for lettuce because it, too, has flowers that hoverflies and parasitic wasps enjoy.

Root crops as basil companion plants

Root vegetables, such as beets, carrots, radishes, parsnips, onions, and even garlic make good companion plants for basil. Why? Well, for a few different reasons.

1. Onion thrips: As discussed in the tomato section above, onion thrips have been shown to be deterred by the presence of basil. These pests cause distorted leaf growth on onions and garlic.
2. Carrot rust fly maggots: When carrots and parsnips are grown side-by-side with basil, they have a reduced tendency to be attacked by carrot rust fly. The maggots of this fly chew through the roots, leaving tunnels and rot behind.
3. Radish maggots: The larval stage of a tiny fly, radish maggots cause damage that’s very similar to that of the carrot rust fly. Interplanting with basil may help reduce egg-laying behaviors. This is sometimes challenging for northern gardeners, however, since radish is a cool-season crop and basil is a warm-season crop, so growing radish and basil at the same time is not the norm.

Also, if you plan to save seeds from any of these root crops, leaving basil plants flower nearby may help enhance the population of the small pollinators that pollinate the flowers of these root crops.

Potatoes as companions to basil

The last vegetable crop to partner with basil are potatoes. While the benefits of this combination are not as solid as the others discussed in this article, there was a study that looked at basil’s ability to enhance the rate of natural predation of larval Colorado potato beetles on potato plants, particularly by parasitic wasps. It showed a modest difference, but it’s worth giving it a try.

Flowers as basil companion plants

Lastly, there are also some great flower companions to grow with your basil, including marigolds, chamomile, borage, chives, and rosemary. Not only do they share many of the same pollinator species, they all also produce edible flowers, just like basil. Toss them in salads and enjoy the diversity of flavors.

You can’t go wrong with basil

While basing plant partnerships on science is always a good thing, keep in mind that there are few, if any, plants that should not be planted with basil. In other words, basil goes great with everything! Harvest what you’d like, then let the plant produce flowers to help draw in the pollinators and predatory beneficials that provide so many benefits to the garden.

For more information on growing great basil, visit the following articles:

• Pruning basil for bigger plants
• Growing basil from seed
• Growing basil from cuttings
• Types of basil

Pin this article to your Vegetable Gardening board for future reference.