To get rid of fungus gnats, mix a solution of one part hydrogen peroxide with four parts water. Pour the mixture onto the soil around the infested plant. The peroxide will help to kill the fungus gnats and prevent them from returning.
Mix 1 part 9% hydrogen peroxide with 6 parts water. Allow top layer of soil to completely dry out before drenching the soil in the peroxide solution. Did It Work? The peroxide drench was very effective in killing larvae, although it never completely killed off the gnat population within the 3 weeks I used it.
Like our cuts and burns, the soil will begin to fizz and bubble, signaling its decomposition into water and oxygen. Hydrogen peroxide will kill all adult gnats and larvae it touches. It is safe to use this solution once a day for as long as it takes to eradicate the gnats and larvae infesting your house plants.
If you use a higher concentration of hydrogen peroxide on the foliage of the plant you run the risk of burning it. You could burn the roots, but since it's necessary to kill the root rot-causing bacteria, it's a risk worth taking.
The water and hydrogen peroxide solution will foam and fizz a little when it comes into touch with the growth medium, which is to be expected. On contact, it destroys fungus gnat larvae. The fizzing will stop after a few minutes, and the hydrogen peroxide will decompose into safe oxygen and water molecules.
Treat the soil.
Use 1-2 tablespoons of hydrogen peroxide per cup of water, and mix enough to saturate the entire root ball. Mix well, then apply to the soil. Hydrogen peroxide is root safe though it can look a little scary, because it will begin to bubble up when poured in.
Water your plant with a mixture of one part hydrogen peroxide and four parts water. The solution will kill the larvae, but is harmless to your plant. Reapply the hydrogen peroxide solution once a week until you see that the fungus gnats are gone.
Unlike hydrogen peroxide, neem oil solutions kill both larvae and fungus gnats and thereby speed up the process of eliminating the pests for good. To create a neem oil spray, simply mix a teaspoon of dish detergent with a gallon of water and two tablespoons of neem oil.
Fungus gnat larvae usually are located in the top 2 to 3 inches of the soil, depending on moisture level, and primarily feed on plant roots, fungi, and decaying plant matter. Gnats are not strong fliers and emerge from soil when disturbed.
Fungus gnats are also capable of spreading the plant pathogen that causes damping off and the eventual death of seedlings. Fungus gnat damage will appear similar to that of any other root-related issue, such as root rot. Lower leaves may turn yellow and drop, and the plant's growth may slow down or stop completely.
Mosquito bits are little pellets that contain a bacteria that's toxic to fungus gnat and mosquito larvae. You scatter them on top of your soil or let them sit in your full watering can for a few hours or overnight to marinate.
For planted seedlings: Spray with H2O2 solution of 1 part H2O2 3% to 32 parts water (eg: around 30mls per 1 litre - measuring cup recommended). For established plants: Mix 1:1 ratio of 3% H2O2 and water (eg: 1 cup of each). Bottom or top water as usual (water soil only, do not pour on leaves).
Dish soap does not directly kill gnats on its own. Liquids like vinegar need surfactants like dish soap to break their surface tension and drown insects. Due to the fruity scent of this gnat solution, it lures the gnats and causes them to get stuck and die in the solution because of the dish soap.
There are natural insecticides, including pyrethrin and azadirachtin, that effectively treat fungus gnats at various life stages. Other natural ways to get rid of fungus gnats involve setting out sticky traps or a homemade gnat trap using one part apple cider vinegar, one part water, and a few drops of dish soap.
Make the natural habitat inhospitable. This means drying out the soil they live in because fungus gnat larvae need moist soil. If you let it dry out completely before your next watering, it will get rid of the gnats in the soil and discourage new adults from laying their eggs.
Mixing half a cup of isopropyl alcohol with a teaspoon of dish soap in a spray bottle, and spritzing it directly on to the gnats will quickly kill the gnats.
In a small bowl, mix a half cup of warm water plus two tablespoons of apple cider vinegar, a tablespoon of sugar, and about six drops of liquid dish soap. Gnats will be lured in by the sugary mixture, but once they dip in for a drink, the sticky dish soap will trap them.
The gnats will be attracted to the scent of the vinegar and fly in for a sip. Meanwhile, the dish soap works to cut the surface tension of the vinegar, causing the fungus gnats to fall in and drown.
Just like using coffee grounds as a fertilizer, the best part of using cinnamon to boost plant health is that it's completely safe and non-toxic. 'Unlike chemical pesticides, fungicides, and fertilizers, cinnamon won't harm beneficial insects or contaminate your soil and water supply,' Richa notes.
When using hydrogen peroxide for plants, the solution is generally diluted, making it safe for roots. To make a safe hydrogen peroxide mixture, start by mixing 1 part hydrogen peroxide with 9 parts water. Next, soak the roots in the solution for 30 minutes.
For the most effective pest control, it's best to spray once per week until you see results. Additionally, using hydrogen peroxide to get rid of larvae in your plants can be a great alternative to chemical-based options. Mix 1/2 cup of H2O2 with 2 cups of water, and water your plants thoroughly.