Growing herbs is a wonderful pastime for gardeners and aspiring chefs alike. That said, herbs can be very sensitive to environmental changes. As a result, you may have to deal with issues like discoloration, unwanted insects, and disease. If you’re wondering “why is my basil turning brown?”, read on. We might be able to help you pinpoint the issue so you can remedy it now, and prevent it in the future.
Why is My Basil Turning Brown? What Am I Doing Wrong?
There are a few reasons why the basil in your containers or garden might be turning brown. That doesn’t mean that you’re doing anything wrong! Basil is a very temperamental herb, and it can go wilty and brown at the drop of a hat.
Related Article: Why is My Basil Plant Wilting?
When you’re examining your plant, be sure to examine it thoroughly. This way, you can determine whether there are other symptoms that can tell you what’s going on. For example, if the soil is super dry and there aren’t any fuzzy spots on the plant, it’s probably a case of underwatering. In contrast, if there are streaks on the stem and leaves, you may be dealing with thrip damage and a fungal disease.
Below are some of the most common reasons why basil goes brown. Some of them have easy remedies, while others require a bit more drastic action.
Over (or Under) Watering
Basil needs consistent watering, but it doesn’t like to get too drenched. If it receives more water than the surrounding soil can drain efficiently, the roots will drown. This means that they’ll start to degrade, and the plant won’t be able to draw any moisture up into the stem and leaves.
The end result to this is that the leaf ends will go brown and dry. They’ll start to curl up and go brown, and will fall off rather quickly.
To keep your basil watered consistently, check the soil daily. You can do this by poking a finger down into the dirt all around the plant. Allow the soil to dry out to at least an inch deep (or just beyond your first knuckle) before watering it. This is a great way to ensure that your basil gets an ideal amount of water.
Additionally, make sure that your basil plant’s soil is sandy and well-draining. This will keep water from accumulating around the roots.
Basil needs a lot of sunshine to thrive. And we mean a lot.
Remember that this plant originated in Southeast Asia. It likes balmy weather, and a good eight to ten hours of bright, happy sunshine daily. If it gets insufficient sunshine, it’ll keel over and die of sadness.
Okay, not literally sadness, but it’ll certainly look that way.
If you’re a novice gardener, plant your basil in pots instead of right in the ground. This is because the other plants around this herb might shade it out as they grow. What this means is that if these plants grow taller than the basil, they’ll block sunlight from reaching it.
Further Reading: Why is My Basil Flowering?
When you grow herbs in pots, you can move them around easily. This way, if taller plants are shading out your basil, just move the pot to a sunnier location. Keep pruning it regularly, and bring it inside over the winter. You’ll be able to grow your basil year-round on a sunny countertop!
There are a few diseases that can turn your basil plant brown too.
This soil-based pathogen can affect just about any plant. It’s vicious and aggressive, and will spread indiscriminately through species. It starts off as brown streaks appearing on the plant’s stem. The plant will get wilted and its leaves will go yellow before dropping off.
There’s no treatment for FW. All you can do is remove and burn any affected plants. Then you either have to dispose of the soil in a dedicated drop-off point for sterilization, or treat it yourself. You can saturate it with boiling water, and then treat it with a strong biological fungicide. Then, don’t plant anything in there for at least two years.
Impatiens Necrotic Spot Virus
INSV tends to be spread by insects, especially flower thrips. The basil plant’s leaves will be mottled or splotchy brown, and they’ll fall off if you touch them. You can try to treat this issue with an insecticide, but it’s often better to just burn any affected plants.
There are a few different mold diseases that can affect basil plants, and the two most common are gray mold and downy mildew. Both will cause your basil plants to turn brown, with fuzzy growth on and under the leaves and leaf stems.
Try to water your herbs at soil level to avoid moisture accumulation on and under the leaves. Prune the leaves often so they get plenty of air flow. This will dry out any potential damp pockets, and will also dissuade insects from getting too comfortable.
Remember that plant viruses can’t transfer to humans or animals. Exposure to fusarium wilt or INSV won’t cause you to suddenly break out in moldy spots. Just make sure to wear gloves when handling these, and wash your clothes and skin thoroughly. This way, the plant pathogens can’t transfer to your indoor plants, nor anywhere else in your garden.
We mentioned earlier that INSV virus is transmitted by thrips. These tiny insects like to nest in soil-level detritus such as fallen leaves. They crawl all over plants, sucking out their juices and leaving silvery trails behind on the leaves. These leaves quickly turn brown and fall off.
Aphids also like basil plants, and can devastate your entire herb patch if allowed to run unchecked.
Beneficial insects like ladybugs and earwigs help to kill and eat aphids. Additionally, you can get organic pesticides that target aphids.
One of the best treatments for just about all crawling insects is diatomaceous earth (DE). This stuff is basically silica from streams and other waterways. It’s all organic so it won’t harm your animal companions, and is completely nontoxic. Keep it on hand in case aphids or thrips show up, and act quickly if and when they do.
You might just save your plants!
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Is Brown Basil Still Edible?
As long as it isn’t slimy, yes. If it still has a strong fragrance when you rub or chop it, it’s fine: just discolored. In contrast, if the leaves seem to fall apart when you handle them, they’ve already started to degrade.
Provided that your plant has turned brown because of insufficient light or water, just compost it. The basil will add some extra nitrogen to the compost heap, and will nourish other plants next season.
On the other hand, if it died because of a pathogen or insect damage, burn it instead. This will prevent your compost bin from being contaminated by the same issues that killed your plant
All of these issues might seem a bit intimidating, but they’re all easy to prevent or treat. If you put some extra effort into taking proper care of your basil, you’ll be making pesto for years to come.