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How To Get Rid Of Gnats In Grow Tent- Effective Ways?

Several kinds of ants, insects, and flies attack the houseplants and keep living around until the crops are entirely ruined. Fungus Gnats are one of those common bugs.

These creatures come to any plant, attracted by the wet soil, as this is an ideal place for them to live and grow. If you do not destroy the pests immediately, your plants will suffer severely and die by diseases initiated from Fungus Gnats.

Before starting a war against Fungus Gnats to save your plants in a grow tent, you must know the basics of your plant’s enemies. That includes,

  • What kind of creatures are these, and how do they harm?
  • And how to prevent them from coming to your plants?
  • More importantly, how to get rid of gnats in grow tent?

What are Fungus Gnats?

I am assuming you are here, after seeing Fungus Gnats around one of your plants, but still confused about what that tiny black creature is and what are they doing in your grow tent.

Let me describe what you have seen from a microscope viewpoint.

Fully-grown Fungus Gnats are more or less 2mm long, have a darker body with transparent wings. The first thing you may notice might be its shiny-black head. However, the larvae are white and lengths up to total of ¼ inches.

A Fungus Gnats completes its life cycle within a month. It goes from the egg to larva first, then to the pupal stage before transforming into a fully grown Fungus Gnat. An adult fungus gnat lives only a week or a bit more and lays up to 300 eggs within this time.

That pretty much indicates, around one plant, you can probably see multiple generations of Fungus Gnats. Absolutely unpleasant!

Confusing Fungus Gnats with Other Pests- Mosquitoes or Fruit Flies?

Spotting a tiny bug and identifying it instantly is not as simple as it seems because there are hundreds of indoor pests worldwide. So knowing the most common bugs and their resembled creatures are the best you can do.

At first sight, Fungus Gnats may look like mosquitoes because of their long legs and nearly similar transparent wings. But when you look closely, most probably, you can tell the difference in size as mosquitoes are comparatively more giant (3mm-6mm) than Fungus Gnats.

Another creature that growers confuse with Fungus Gnats is the fruit fly. These pests are tiny and fly around the plants, so it is hard to differentiate for a newbie grower. But here are a few tips to recognize if the pest that invaded your grow tent is fruit flies or Fungus Gnats-

  • Color– Fungus Gnats have a gray-black combination, and fruit flies have a yellow-brown mixture. If you notice carefully, the darker one has the most chance to be Fungus Gnats, and if it is pale or tan brown, it should be fruit flies.
  • Size– Fungus Gnats are a bit smaller in size than fruit flies.
  • Living area– Fungus Gnats live around the wet soil of the plants and reproduce there, whereas fruit flies can be seen more around ripped or rotten fruits and vegetables.
  • Preferred spots– If you maintain proper cleanliness in your grow tent, there is a high chance the bugs you have are Fungus Gnat. As in, fruit flies prefer drains, trash cans, garbage bins, or empty buckets to breed.

How Does Fungus Gnats Harm the Plants?

We mostly think the adult Gnats, which we can see, are causing harm to the plants, but in reality, little ones, which we cannot see with bare eyes, are the prime enemy.

Adult Fungus Gnats lay numerous eggs in damp soil as it is ideal for these creatures to breed and develop. While these larvae grow to the fullest, they eat anything edible in that soil, including the root hairs, and clog the soil during digestion.

In this process, the larvae spread diseases that severely harm the plant’s roots. It damages the growth and leaves of the crops. However, the significant danger it brings is to the seedlings.

If Fungus Gnats attack the plants at the seedling stage, it eats up the tender roots, and at this stage of the plant, there is hardly any chance that the seedlings could grow any further.

If this pest infests the flowering stage, the plants may still survive after proper treatment, but the yield will be reduced noticeably.

How To Get Rid of Gnats In Grow Tent?

If your plants in a grow tent are infected by Fungus Gnats, you can choose from tons of products and natural home remedies. We have divided the invasion of Fungus Gnats into 3 stages. Thereby, we’ll guide you on what you should do according to the stage of Fungus Gnats infestation you are in-

A quick tip: If you are unsure which stage of invasion your plants are in, you can always use yellow sticky traps and decide after analyzing the number of insects on the baits.

Initial Stage

Here we are assuming you have recently spotted Fungus Gnats around your plants and taking the necessary steps right away. There are these few products and activities we suggest you apply and follow to get rid of the pests completely:

Yellow sticky traps

Yellow sticky traps are cheap and effectively capture Fungus Gnats. It helps to understand a bit of the present invasion situation your plants are in and also drives the insects away from your plants.

You can place these traps in different shapes and sizes. However, try to place it in such a way that would take out most of the insects.

You might think of using flypaper instead of yellow sticky traps because it is available and has a similar mechanism. But to acquire the best result from these traps, we would strongly recommend using yellow sticky traps as the color ‘yellow’ immensely attracts the bugs toward them.

Reduce the moisture

By this time, it is pretty clear that the primary reason for the pest to attack the plants is because of damp or wet soil. This particular condition is ideal for their survival, thereby reducing the humidity or moisture level of the soil can significantly benefit the plants in this circumstance while at the same time helps to get rid of the insects.

You can invest in additional fans around the pest-affected plants. It will both force the adult Fungus Gnats to go away and dry the soil quickly, making the larvae or maggots’ life miserable.

Don’t make the soil too dry though, otherwise, it will backfire and cause you unwanted problems alongside the pest invasion.

Neem oil

Neem oil is a natural remedy and has been a great help to destroy Fungus Gnats’ invasion in indoor areas as it kills the Fungus Gnats immediately.

Spray the oil with a pressure sprayer for even and easy oil distribution. Try to spray it on the bugs and larvae directly to ensure an instant kill.

If your plants are near the harvesting stage, be extra careful while spraying the oil over plants. Be sure to avoid the flower buds; otherwise, neem oil will cause alteration in the crop’s taste.

Apple Cider Vinegar and Dish-soap mixture

Most of the growers have already heard of this homemade mixture. It is widely used to solve different cases of bug invasion and works pretty well with Fungus Gnats.

Firstly, you would need a small bowl or unused can, which must have a depth of 1/2 inches. Then, mix an equal amount of apple cider vinegar and water. At the end of mixing, add a few drops of any liquid dishwasher soap and stir it to make a sticky solution—no need to initiate bubbles.

This mixture will work as bait while you place it on the soil. The pests will dive right into it and be unable to move or fly back. Make sure to change the mixture once a week.

Intermediary Stage

Suppose you have recently identified Fungus Gnats, but these creatures have already increased in number before you could even think of a helpful resolution. In that case, you need to apply a few higher-level items besides the beginner solutions.

Hydrogen Peroxide

You can apply a food-grade hydrogen peroxide mixture to kill an average number of Fungus Gnats. This remedy is not scientifically recognized and still gets your job done to some extent.

Generally, to gain 3% pure H2O2, mix 1-segment of hydrogen peroxide with 4-segments of water (1:4) and use a solid force to sprinkle this mixture on the bugs directly.

Essentria IC3 Insecticide

If you ever dealt with bed bugs, you must have heard about this particular insecticide by now. It is mainly known as “Bedbug Killer” in the shop but also provides satisfactory results in removing Fungus Gnats all the way.

Essentria IC3 has a variety of oil that is organic and used in horticulture. You can use this insecticide pretty much every other day to control the outbreak. Also, it is easy to combine this item with other necessary products to bring better results.

Unlike most other insecticides, this one is risk-free for both humans and pets. Just remember to use it with a ‘One-hand-pressure’ sprayer to spray all over the place in a precise manner.

Diatomaceous earth powder

Diatomaceous earth is an organic matter from fossilized shells and is nicknamed “Grass of the sea.” Its reaction is lethal to the Fungus Gnats while precisely opposite to the human.

It kills the bugs on a microscopic level by penetrating the bug’s exoskeleton, which leads its body to dry up by losing body fluids. It kills the larvae fast and also serves as a prevention to the future attacks of Fungus Gnats.

The powdery diatomaceous works the best to kill, and it needs to be used with a powder duster. This organic powder contains silica that perishes Fungus Gnats from the core. Surprising enough, this same fatal thing is safe and even edible for humans and pets.


SM-90 is not an ideal solution that comes from an insect expert. But it is commonly used by experienced growers as they get positive results continuously.

To use this mixture, add 1-segment of SM-90 and 5-segments of water, mix it lightly and spray with a pressure sprayer. This solution has also proved beneficial for plants while causing no danger for humans and pets and being deadly with the adult or larvae Fungus Gnats.

Final Stage

In the final stage, we consider your plants are enormously suffering from the diseases caused by Fungus Gnats. Now you must dive into some solid and high-end chemicals to ensure the safety of the rest of the plants unaffected by Fungus Gnats.

Musca-stik fly traps

Musca-stick is another flytrap, slightly advanced, that ensures more kills than yellow sticky traps. It is assembled with glued-bright orange paper on a stick and a catch basin to keep the bar stand straight. The catch basin also works as a surface to contain the provided fly attractant.

Start with sprinkling the pheromone granules inside the catch basin, it will lure the flies towards the stick, and once the bug touches the stick, it is nearly impossible for the Fungus Gnats to move because of the glue, so it ends up dying there.

Usually, you will see 12 inches or 24 inches Musca sticks in the market. You can hang them or keep them on a surface where you frequently notice the pest’s activity.

And don’t forget to keep it out of children’s reach and follow proper disposal.

Growstone Gnat Nix

Gnat Nix is made from recycled glasses and can be used as a soil’s surface dressing. As a result, the top portion of the soil will become unattractive for the adult female Fungus Gnats to lay eggs. Also, the larvae stuck under Gnat nix may become adults but cannot resurface themselves to the top and so they die inside.

This compound has been tested in universities and proved to be fruitful in reducing insects as well as a prevention method.

Mosquito Dunks or BT Bacteria

Bacillus thuringiensis, mostly known as BT-Bacteria, is a biological pesticide that works feasibly to kill the larvae or maggots without harming the plants, humans, or pets.

Now how to use this bacteria? You can go for mosquito dunks; the pellets of mosquito dunks contain this bacteria. As written in the instruction, you do not need to use one pallet at a time. You are allowed to take as much as needed and then crush it before making the solution.

It stays in the soil comparatively longer and kills the larvae by making them unable to eat.

Since biological methods are most effective yet the safest, you might want to experiment with a few other options. For that, you can try predatory mites, nematodes to control the infestation.

How can I prevent Fungus Gnats invasion in my grow tent?

You must have heard; prevention is always much better than cure; we suggest the growers take a simple preventive measurement before learning it the hard way. Alerting by these simple details delineate below, you can eventually avoid a catastrophe and suffer from its loss.

Check the watering routine

So far, over-watering is the leading cause behind the presence of Fungus Gnats in a grow tent. That is why you need to re-check the watering routine of your plants.

Make sure you have a sound drainage system so the excess water can leave the soil. Also, run extra fans around the plants till it dries out 2/3 inches on the top surface of the soil.

If there is no wet/damp soil, that particular place will no longer be attractive to the Fungus Gnats. Consequently, your grow tent will be safe from their invasion.

Disinfect the soil

Before using the soil, bake it for 30 minutes at a high temperature, preferably 80-90 degrees Celsius. This process will sterilize the soil by reducing the risk of pest invasion or any disease.

Though cooking the soil emits the existing larvae, it isn’t a fruitful way to remove clones. Take other possible ways to destroy clones from the soil if necessary.

Cover the surface

Covering the top and bottom of the soil is another commendable way to prevent infestation. You can hide the soil with sand, give it a few inches height (not more than 2/3 inches, or the water will be clogged in the soil).

So the Fungus Gnats larvae will not be comfortable developing on the soil and have to leave the place.

Different growing media

If you are in such an area where it is hard to control the bugs constantly, you might consider growing hydroponically or using cocoa instead of soil. Because these growing mediums hardly attract insects.

Seal the area

Sealing the grow tent area is one of the primary actions to behold all the improvements you have done till now or are going to do. That is why you need to inspect every corner. There shouldn’t even be any tiny hole in the tent. Use screens on the window if you must keep the windows wide open for ventilation.

Set Traps

You may consider using yellow sticky traps or any other bug trapping options all year round. It will let you know the fastest way possible whenever the insects attack your plants.

It helps you take action in the initial stage when you still have a high chance of winning against these bugs and saving the crops.

Frequently Asked Questions (FAQ)

1. What smell do gnats hate?

Ans. Fungus Gnats hate the smell of vanilla, lavender, and even lemon. You may spray these ingredients mixture around the tent or light citronella candles to drive them away.

2. At what temperature do Fungus Gnats die?

Ans. Gnats usually live on warm and hydrated soil. These insects easily tolerate 77 degrees Fahrenheit, even higher, without showing any discomfort.

3. Will these Fungus Gnats go away on their own?

Ans. No, they won’t. Once these pests find a suitable place for their living, the female gnats lay uncountable larvae, and the life cycle goes on for them. Unless you trash all the infected plants or take immediate action to dry out the soil, there is no chance the infestation will stop on its own.

4. What can I use instead of sand to cover the soil?

Ans. You might consider gravel or perlite if sand is not your first option to cover the soil.


Fungus Gnats are not an easy opponent to deal with as they constantly increase their numbers as well as risk to the plants. But also, by knowing how to get rid of gnats in grow tent and taking advanced measurements, you might protect some of the crops from completely ruining.

All the efforts to get rid of the gnats need to be continuous and effective if you aim for a positive result. Otherwise, it is impossible to avoid the outbreak.

This post first appeared on Best Grow Tent For Indoor Gardening, please read the originial post: here

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How To Get Rid Of Gnats In Grow Tent- Effective Ways?


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