Basil is a fragrant annual herb popular in home gardens due to its culinary versatility and distinct aroma. Gardeners often use companion planting, grouping certain plants together to create a mutually beneficial environment. This technique improves garden health, maximizes yields, and provides natural protection against common garden pests. Understanding basil’s good neighbors can significantly enhance the success of your vegetable patch.
Companion Plants That Support Basil’s Growth
Certain plants are beneficial companions because they help basil grow larger, retain flavor, or protect it from environmental stress. Aromatic herbs like chamomile and chives support basil by potentially increasing the concentration of its essential oils, intensifying its flavor and natural pest-repelling abilities. Chamomile flowers also attract beneficial insects.
Oregano serves a dual purpose as a low-growing ground cover, shading the soil and retaining moisture around basil’s roots. Since basil requires consistently moist soil, this moisture retention helps prevent the plant from drying out and bolting prematurely. Borage, a flowering herb, attracts pollinators like bees. Its deep taproots draw up minerals from the subsoil, making these nutrients more available to the shallow-rooted basil.
Taller, sun-loving vegetables, such as eggplant and sweet peppers, are suitable companions for basil. These plants share similar needs for warmth, full sun, and rich, well-drained soil. When positioned correctly, a tall plant like eggplant can offer filtered shade during the hottest part of the afternoon, which helps prevent the basil from scorching in intense heat. This allows the basil to maintain lush foliage and a slower growth rate.
Using Basil to Protect Other Vegetables
Basil’s primary function in companion planting is acting as a natural, aromatic defense mechanism for high-value crops. The herb’s leaves and stems release volatile organic compounds, such as linalool and eugenol, that disrupt and confuse common garden pests. These compounds mask the chemical signals insects use to locate their preferred host plants, creating an olfactory barrier.
The most well-documented pairing is between basil and tomatoes, where the herb deters the destructive tomato hornworm. Interplanting basil directly between tomato plants confuses the female moth searching for a place to lay eggs. This reduces the number of larvae that hatch on the tomatoes, providing an effective, non-chemical method of control.
Basil is also effective against smaller, soft-bodied pests like aphids and thrips, which often attack peppers, roses, and other garden plants. Its aroma is unpleasant to these insects, causing them to steer clear of the surrounding area. Gardeners can plant basil densely around the edges of susceptible crops to establish a protective border.
Specific basil varieties can target different pests, such as lemon basil repelling whiteflies. Basil can also repel the asparagus beetle, creating a mutually protective relationship for crops like asparagus. The best placement strategy is to intersperse basil plants throughout the garden beds, rather than grouping them in one area, to ensure the protective aroma is widely distributed.
The herb’s protective qualities extend to root vegetables, where its scent confuses pests that target the leafy tops of carrots, beets, and radishes. Planting basil alongside these crops helps deter pests like carrot flies and certain mites and weevils. This strategy provides defense from both above-ground and flying insects that might otherwise damage the foliage.
Plants That Inhibit Basil’s Success
Not all garden pairings are beneficial; some plants actively hinder basil’s growth and success. Fennel, a member of the carrot family, is widely known for its allelopathic properties, meaning it releases chemical compounds that inhibit the growth of many other plants, including basil. Planting fennel nearby can lead to stunted growth and reduced vigor.
Aggressive, fast-spreading herbs like mint must be contained before being planted near basil to prevent resource competition. Mint is a vigorous grower with a dense root system that rapidly consumes available water and nutrients in the soil. If not planted in a pot or with a root barrier, mint will quickly outcompete basil for necessary resources.
Certain aromatic herbs, such as rue and sage, are poor companions for basil. While the exact chemical interaction is complex, these pairings are believed to dull the flavor of basil or suppress its development. It is best to keep these herbs separated from basil to ensure it maintains its potent flavor and healthy growth.