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That’s nasty.

You see gnats hovering around your potted plants. Not a good sight.

You need to do something about them. You heard that bottom watering may help keep them away. But does it work?

Bottom watering will prevent gnats because it allows the roots to absorb moisture without making the top of the potting soil too damp. Gnats prefer the moist environment that damp potting soil can create.

In this post, I’ll help you figure out how to get rid of gnats from your potted plants and how to prevent them from coming back again.

Keep reading to know more.

Check out the best plant containers on Amazon.com that can help you with your container gardening.

Can bottom watering prevent gnats?

Bottom watering is the process of putting the plants into a bowl of water. This allows the roots to absorb the water. There are a few benefits to this approach, these include:

  • Helping the plants develop strong roots
  • Keeping the soil moist

But to understand how it affects gnats, we need to first know what makes a plant attractive to these pests. Some elements that they will look for include: 

  • Organic matter. This is why gnats can pose a problem for plants. They have been known to feast on the organic matter in the soil. Sometimes, they have been known to eat seedlings. In more established plants, they might eat the root systems. This is why plants that have a gnat infestation will wilt. 
  • Moisture. This is something that gardeners will be able to control. Gnats will be attracted to moist soil, laying their eggs inside it. 
  • Light. Sometimes, bright lights around your plants can be enough to attract gnats. They like to flock to these sources at night. The condition of your garden will determine whether they stick around. 

Since moisture is one of the most important elements attracting gnats to your soil, the way you water the plants is important. This is why bottom can be a good choice. It is an easy way to prevent overwatering while making sure that the plants are getting enough water.

More importantly, though, there is no need to drench the topsoil. This type of soggy soil is exactly what the gnats rely on to breed. With bottom watering, the roots will absorb the water, while the top of the soil will remain relatively dry. This should make it harder for gnats to lay larvae. 

Bottom watering helps prevent gnats by minimizing overwatering. When the soil is overwatered, it becomes saturated. Damp soil provides an excellant enironment for gnats to live. – Brian Walker, Founder, The Landscape Tutor 

I asked fellow gardeners if they thought bottom watering would prevent gnats in potted plants. It was surprising to see that many of them did not thing so as seen in the poll below.

Do self-watering pots cause gnats?

Self-watering pots will not cause gnats because it works similar to bottom watering. There is a reservoir at the bottom of the pot that separates the potting soil from the water. The roots wick up moisture from the reservoir.

You should check that the potting soil is not getting too damp when using a self-watering pot that can attract gnats.

There is also a chance that the stagnant water could provide fertile ground for mosquitoes to lay their eggs. When done properly, however, these risks should be fairly low. 

How do I get rid of gnats in my potted plants?

If you have found gnats in your pot plants, you need to take action urgently. If you give them time to get established, they can do a lot of damage. There are a few ways that you can get rid of these pests. Here are some methods that you can try. 

1. Use hydrogen peroxide

Here, you will need to make sure that you get three percent hydrogen peroxide. Mix this with four parts of water. From there, you will spray it on the gnats. The mixture will kill them instantly. It will also be effective against the larvae of the gnats, stopping them from reproducing. 

We should note that when you apply it to the soil, you might hear some fizzing. This is normal and is to be expected. It won’t damage the plants and the mixture will soon be converted back to water and hydrogen. 

2. Get some sticky traps

This is a very simple way of catching the gnats. All you need to do is position the traps around the plant correctly. Then, the gnats will land on them and they cannot fly away again. You should be able to find these traps at most supermarkets. Or you can make your own. You just need to follow these simple steps:

  1. Pick a yellow piece of paper or cardboard. This color attracts the gnats. 
  2. Apply a sticky substance. There are a few that you can use. Use Vaseline or some engine oil. 
  3. Place it around your plants. Try to avoid getting the leaves stuck in the trap. It should be close to the soil, to catch the hatching larvae. 
  4. Replace as necessary

3. You can use dish soap

Another option that you can use is dish soap. It will also work with dishwashing liquid. You’ll need to dilute some of this into your water to form a spray. You might need to use a solution of one part of dish soap to three parts water. You’ll need to spray this onto the plants.  

Gnats are attracted to moist soil, so bottom watering can definitely help prevent gnats. Bottom watering is an effective way to keep yourself from overwatering your plants, and overwatering is what causes the top layer of soil to remain moist for extended periods of time and thus attracts gnats. – Jeremy Yamaguchi, CEO, Lawn Love

4. Consider using neem oil spray

This is an effective natural pesticide, which is safe for plants. But it will be deadly to gnats. You’ll need to spray the leaves. Make sure that you are spraying the soil, where the larvae will live.

This spray might take a little longer to be effective. You might need to keep re-applying it every few days until you see the infection come under control. 

5. Check out mosquito bits

While they are largely used for mosquitos, they have also proven to be useful for stopping gnats. This is very easy to apply. You just need to put it on the soil. Then, as you water, the chemicals will be released, killing the larvae.  

6. Make use of beneficial nematodes

You can also use beneficial nematodes. These are insects that can be added to the soil. They are harmless to plants and won’t affect beneficial insects like worms. But they will attack gnats, eating the larvae. They also protect plants from things like caterpillars and rootworms

7. Remove infested potting soil

Finally, sometimes, the infection might be too advanced for you to control. Here, you might need to remove the soil. As you are doing this, you will need to remove the plant, wash the roots. 

You then have two options. You can cook the soil. If you put it in the oven for around three hours at a temperature of over 120 degrees Fahrenheit. This will kill the gnats and any other insects that are present in the soil. Or you can replace the soil entirely, opting to start from scratch. 

How to prevent gnats in houseplants?

It’s often easiest to prevent gnats from infecting your soil. There are a few ways that you can do this. 

1. Avoid overwatering the potting soil

The best way to stop gnats is by denying them the conditions they need to flourish. The best way to do this is by stopping overwatering, which creates wet topsoil, ideal for gnat larvae. Here are a few tips you can use to give the right amount of water: 

  • Touch the soil. It should have a light color and be dry to the touch. 
  • Have plenty of drainage. You should have somewhere for the water to go. 
  • Use bottom watering. As we mentioned earlier, this can be an effective way of stopping gnats from taking hold. 
  • Water during the early morning. During the heat of the day, the excess water will evaporate. 
  • Think of the plant. Remember, different plant species will need different water levels. 

2. Make use of a neem oil spray as prevention

You can use neem oil to stop an infection. But it can also prevent infection. All you need to do is spray once per week.   

3. Use top dressing or mulching

Using the right type of mulch will give your plants the nutrients they need while protecting them from a gnat invasion.

The thick layer of mulch will be too much for the gnats to get through, stopping them from laying their eggs.  Some of the best options are inorganic mulches, like pea gravel

4. Keep an infested plant in isolation

If you notice a gnat infection, it’s important to act quickly. As a result, isolate the infected plant, putting it in a separate room.

If you do this fast, you will stop the gnat infection from spreading. From there, you’ll be able to focus on getting rid of the pests. It’s a lot easier to treat one plant than it is to fight multiple infections.

Here are some of my favorite container gardening tools

Thank you for reading this post. I hope it helps you with your gardening needs. I’ve listed some tools below that can help you with container gardening. These are affiliate links so I’ll earn a commission if you use them.

Gardening Gloves – I find the Pine Tree Tools Bamboo Gardening Gloves really good for both men and women. It’s made from bamboo so helps absorb perspiration. They are also comfortable and fit very well.

Containers – You know picking the right container is crucial for your container gardening. I’ve written a detailed post on the best containers you can choose from. If you’re happy with a plastic container, you can check out the Bloem Saturn Planter.

Watering Can – This is a must-have tool when you’re growing plants in pots or grow bags. It helps to water the potting soil without splashing on the foliage. The Kensington Watering Can is stylish, strong, and can provide precision when watering potted plants.

TrowelGarden Guru Trowel is my favorite because it’s durable and comfortable to use. My gardening friends really love having a trowel because they use it for digging soil, mixing fertilizer, moving seeds, leveling out the soil, mixing compost or mulch, and also dividing tubers

Bypass Pruner – I really like the Corona Bypass Pruner because it’s durable and gives a clean cut that helps plants recover faster. If you’re looking for something cheap, get the Fiskars Bypass Pruner that is really good as well.

To see an extensive list of the best container gardening tools gardeners recommend, check out this resource that I made for you.