The most annoying flies, such as fruit flies and midges, are often the smallest. These tiny pests appear in small swarms that attack your food or even you. However, gnats can pose a special problem.
While it’s common to find gnats outdoors, it’s a warning sign when you see them hanging around one of your indoor plants.
When this happens, it’s important to get rid of this annoying pest and find the underlying cause of the infestation.
How To Get Rid Of Gnats In Plants
It can be difficult to get rid of fungus gnats in houseplant soil, but those hanging around your potted plants are even worse.
Before we talk about exterminating them, we should first cover why they’re there in the first place.
These Aren’t Your Average Gnats
There are quite a few species of gnat, but those belonging to six of the seven families in the superfamily Sciaroidea are collectively known as fungus gnats.
Fungus gnats are poor fliers and generally prefer walking to flying.
When in flight, they can be a nuisance, often flying into your face.
Fungus gnats exist both indoors and outdoors, congregating around plants and ground containing fungal growth.
The larval stage eats this fungus (although a few are predatory), while the adults are sometimes pollinators of flowers or mushrooms and sometimes live only long enough to reproduce.
Why Does My Plant Have Gnats?
You may end up with a fungus gnat infestation for a few reasons.
Fungus gnats aid in decomposing matter, which is usually a huge factor in their presence.
For example, if you have too much organic matter in the soil, they will lay their eggs in it so the larvae can break it down. Their larvae will then feed on plant roots and fungi in the soil, causing the leaves to turn yellow or worse, die.
Overwatering can also play a huge role in an infestation. As the name implies, fungus gnat larvae love munching on soil-based fungi.
Overly wet or even damp soil is a perfect fungi breeding ground, drawing in the gnats.
But excess water can also lead to root rot, which may be either fungal or bacterial in nature.
The gnats will be drawn to this rot, meaning an infestation can often be one of your earliest warning signs that your plant is in danger.
Finally, lighting can play a role in attracting fungus gnats, albeit a much smaller one.
As with many insects, fungus gnats are attracted to artificial lights, and you might find them buzzing about grow lamps and decide to set up shop on the plants below.
Chemical Control Methods
The good news is you won’t need to use pesticides to get rid of a fungus gnat infestation.
However, you may wish to use fungicides if your plant has a fungus gnat problem to ensure no underlying fungal infections are present.
Organic Control Methods
Fungus gnats are easily controlled using home remedies and some simple store-bought remedies.
It can be difficult to eliminate fungus gnat eggs, but thankfully eliminating the larvae and adults are a snap using the following methods.
Diatomaceous Earth (DE)
Food-grade diatomaceous earth is an excellent barrier against a wide range of houseplant pests, including fungus gnats.
Sprinkle some DE on the soil of your potted plant.
Any adult gnats or larvae that come into contact with it will be lacerated and die soon after.
However, you will need to reapply every few days as moisture renders this natural remedy null.
Sticky Traps
While fly strips are the most efficient, you can also use other types of sticky traps with great results.
Fly strips are a cheap and effective way to control a fungus gnat population.
Like fruit flies, the fungus gnats are easily caught in the glue.
Neem Soil Soak
Neem oil is a highly effective, all-natural remedy for hundreds of insect species and a natural fungicide.
When neem is used in a soil soak, it also kills pests without harming beneficial ones (such as beneficial nematodes and earthworms). It can combat many bacterial infections and invasive fungal infections.
This remedy won’t harm adult fungus gnats, but it can kill the larvae and is good for your plants’ health overall.
You can grab a spray bottle to spray the top of the soil using this insecticidal soap solution.
Best of all, you only need to reapply once every 3 weeks to be an effective preventative treatment.
Related: Why should you consider neem oil for fungus gnats?
Potato Trap
Fungus gnat larvae are attracted to starchy tubers, so you can capture them using potatoes.
Simply cut a potato into small chunks and place the chunk on the soil surface around the base of your plant.
Check the chunks every few days for signs of larvae burrowing into them, and discard any infested chunks.
When used in conjunction with methods that target adults, this is a surprisingly effective way to eliminate a population.
Vinegar Traps
Vinegar traps also work well for this purpose and are easy to make. Learn how to use vinegar to get rid of fungus gnats on indoor plants.
One popular method is using a small soda bottle with the top cut off and then taped upside down to create a funnel that the gnats can’t fly back out of.
Add some apple cider vinegar, and the gnats will climb into the bottle and get stuck.
Another is to use a small clear container with some vinegar and a few drops of liquid dish soap, covered with plastic wrap with a small hole.
Change out the vinegar couple of days as needed.
Go natural: Check out this article on Getting Rid of Fungus Gnats using Cinnamon.
Preventing Future Gnat Infestations
Of course, no matter how easy it is to get rid of a fungus gnat infestation, it’s far better not to get one in the first place.
Thankfully, it doesn’t take much to accomplish this, and almost everything comes down to basic care.
Limit Organic Matter
Don’t overdo it when adding organic matter to your soil.
This includes compost and other organic material that may decompose slowly if you add more than necessary.
This matter will attract the fruit flies, and adding an excessive amount won’t do anything to help your plants.
Practice Good Watering Habits
Overwatering can lead to many problems, but proper watering can help prevent this risk.
Never water your plants using a calendar, as there will be times when they need more or less based on several variables.
Instead, use either the soak-and-dry or bottom-up method, as both allow you to judge when your plant has the right amount of water.
Also, unlike overhead watering, these two methods give you evenly moist soil without getting the foliage wet (which can also lead to fungal infections).
You should also use the finger method (or another technique) to judge when you have sufficient dry soil to warrant a drink instead of guessing.
Letting the top few inches of soil dry out completely between watering sessions is also a great practice.
Moreover, always ensure your container has proper drainage holes to get rid of gnats naturally.
Prune Regularly
Fungus gnats are attracted by decaying organic matter, so one great way to avoid the risk of attracting them is to prune away any dead parts of your plant before they begin to decay.
Self-cleaning plants will do this step for you, but you will still need to collect the fallen bits.
Keep an eye on any pruning restrictions your plant has, and try to work within those limits to ensure you’re not harming the plant in the process.
Use Only Quality Potting Soil
One of the reasons many off-brands of potting mix are so cheap is that they skip the sterilization step.
This means it’s possible the soil you bought could already be harboring an infection or infestation.
Instead, only buy reputable brands, even though they may cost a bit more in the short term.
One of the things that makes Miracle-Gro so great is that it’s a highly trusted brand that still keeps its prices affordable, and there are other great brands out there you can safely save money on if you do a little research.
Also, be sure to repot your plants every few years with fresh soil to eliminate toxin build-ups and reduce the risk of the old soil developing a fungal infection.