Why Your Basil Plant Is Wilting—and How to Fix It, According to Experts

Basil is a favorite herb for so many reasons—it has an inviting fragrance, imparts a lot of flavor, and is easy to grow. Even more importantly, this low-maintenance herb makes a lovely addition to any garden—both indoors and outside. But what happens if your basil plant begins to wilt? When wilting occurs, the health of the plant may suffer and if you don’t take steps to address the underlying problem, your delightful plant may struggle to thrive and grow. Luckily you can prevent many of the issues that cause wilting and have your basil plant looking great again in no time with these tips and remedies from experts.

Underwatering

One common reason basil plants wilt is lack of water. But there’s an easy test you can perform to check. “To see if wilting is caused by underwatering, pull back any mulch and then put your finger in the soil up to your first knuckle,” says Angela Judd, master gardener. “If there is moisture in the soil, your finger should get dirty, and the soil will feel moist. If your finger comes out clean, there is not enough moisture, so it's time to water,” she says.

Overwatering

Even though water is vital, too much of a good thing can be detrimental, so make sure you don’t overwater your basil. “If basil is overwatered, the leaves will droop and turn yellow; they may also have brown or black spots on them,” says Kathy Jentz, author and host of the GardenDC Podcast. “If you notice that the soil is wet and wilting occurs, stop watering it for a week or so to let the soil dry out.” The roots of your basil plant need to be able to access oxygen present in the soil, and if there’s too much moisture in the soil, you can essentially drown the roots.

Disease

Overwatering can also encourage fungal diseases to attack basil. Leaf spot, root rot, and fusarium wilt are common in basil. While leaf spot and root rot can be remedied by adjusting your watering schedule, there is no effective cure for fusarium. Once you see symptoms of this disease, pull the plant out and discard it immediately so it doesn't spread to surrounding plant, says Jentz.

To prevent fusarium in the future, choose basil plants that are resistant to the disease such as 'Nufar,' 'Aroma-2,' 'Prospera,' and 'Obsession,' says Jentz. She recommends not planting basil in the same soil that the fusarium wilt initially occurred as the spores can stay in the soil for several years.

Pest Infestation

Some common garden pests can also give basil a wilted appearance. Frequent visitors to basil include aphids, slugs, Japanese beetles, and spider mites. How you handle the situation may depend on the pest. If the infestation is light enough, you might be able to physically remove the pests from your basil. You can also try a barrier like transparent garden fabric that will keep the bugs out but still let the light in. 

Lack of Nutrients 

Even though basil obtains most of its structural mass from carbon in the air, it also extracts nutrients from the soil, too. So if your basil is wilting, it’s possible the soil itself is lacking in some way. “The best way to tell if there are nutritional deficiencies is with a soil test and then feed the soil based on those recommendations,” says Judd.

One way you can increase the microbial life and fertility of the soil is by adding worm castings and compost. Microbes present in the worm castings can convert nutrients in the organic matter into forms that plants can absorb. This can also increase the soil's ability to retain nutrients like calcium, potassium, and magnesium, says Judd.

Stress From Transplanting

The stress of transplanting can also cause your basil to wilt. Seedlings that have been cultivated in the warm, moist, and wind-less environment of a home, greenhouse, or garden center may suddenly find themselves in a state of shock when they are uprooted and placed in a new outdoor setting. “To reduce transplant shock, choose young, healthy seedlings,” says Judd. “Their roots should not be circling inside their container, and they should appear healthy with bright green leaves,” she says.

Introduce the seedlings to their new environment slowly. “Harden off seedlings before transplanting by gradually accustoming them to their new surroundings to see how they tolerate any differences in light or temperature,” says Judd. “Provide shade and extra watering as needed after transplanting to protect young seedlings and prevent the small root ball from drying out.”

Temperature Extremes

A significant drop in the outdoor temperature in early spring or late fall can cause your basil to take on a lethargic and wilted look. This often happens when temperatures are around 40 degrees Fahrenheit or lower, as basil can’t handle frost at all. Keep your basil plant healthy and wilt-free by either covering it or by growing it in a container and bringing it indoors on cold nights.

Basil can handle heat extremes more easily than cold extremes. Basil likes sunshine and warm temperatures, but if you’re expecting a particularly hot day, you may want to temporarily provide a light screen of protection to shield your basil from the intensity of direct sun.