1. Insecticidal soap. Insecticidal soap will get rid of most houseplants' problems. Wiping your plant leaves with soapy water can literally remove the pests and their larvae.
A: They're most likely fungus gnats. These little buggers are a really common pest over winter, and they're more attracted to the moist soil in houseplant pots than to the plants themselves.
Try Vinegar for a Gnat Trap
Pour apple cider vinegar into a cup or glass and mix in a few drops of dish soap. Cover it with tape or cheesecloth, leaving holes large enough for the bugs to get to it. The scent will attract the bugs and they sip the solution and drown.
If the infestation isn't heavy, try washing them off in the shower with a strong spray of water. You may need to do this a few times to completely remove the pests. Other options include treating with neem oil, dabbing pests with rubbing alcohol, and sticky fly paper.
Pyrethrum. Like neem oil, pyrethrum is an insect-fighting compound derived from chrysanthemums. Pyrethrins, a synthetic version, also exist. Typically, this pesticide for indoor plants is readily available for spray; therefore, we recommend applying it according to the brand's instructions.
With all that in mind, the EPA says that hydrogen peroxide in low doses is indeed safe for plants. The caveat is of course, in the concentration. Too much can damage plants.
For years, extension specialists, including myself, routinely gave out the recipe for an effective, homemade insecticidal soap which consisted of a specific amount of liquid dishwashing detergent, diluted in water to create about a 2 percent solution and sprayed on the surface and undersides of leaves.
Use one part vinegar (apple cider or white) to three parts water to create a sprayable solution. Add a few drops of mild dish soap to help the solution stick. Add to a sprayer bottle and apply to the base of infested plants. Treat the leaves directly if heavily infested.
For hydrogen peroxide, mix one part 3% hydrogen peroxide with four parts water. Carefully pour this solution onto the top of the soil, ensuring it reaches the root zone. The hydrogen peroxide will help kill the gnat larvae and any eggs in the soil without harming your plant.
The mixture should contain a few drops of dish soap, a tablespoon of vinegar, and baking soda per cup of water. A few sprays of this mixture is an effective gnat repellent. They may be sprayed in areas where gnats are commonly seen, such as around plants, in the bathrooms, etc.
Hydrogen Peroxide
A peroxide solution apparently kills larvae and eggs on contact, effectively killing off all infant gnats and disrupting the lifecycle. You should be able to buy hydrogen peroxide from any high street pharmacy or online.
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.
One way to get mites off your plant is to wipe down the leaves with soapy water. To do so, Brown says to start by mixing a small amount of dish soap with about 1 cup of water. Next, dip a cloth into the solution and fully wet and wipe down the leaves, making sure to also clean the stems and undersides of the leaves.
Does Cinnamon Keep Fungus Gnats Away? No—but the idea that cinnamon could provide a natural method for controlling fungus gnats has some basis in reality. "Unfortunately, you can't count on cinnamon on or in the potting mix to help control fungus gnats," Hancock says.
Over-watering and poor drainage can cause root rot and encourage fungus gnats as well as other pest issues.
2 Steps to Gnat-Free
Discard the soil immediately, and replace this top layer with sand, which is free of organic matter and dries out quickly—an unappealing medium for fungus-gnat eggs. Let the soil below dry out completely before the next watering.
Similar to neem oil, you could use a combination of water and hydrogen peroxide. Mix these together in a container and cover your soil to begin the soil mite removal process. By using this regularly, you should begin to see mite-free soil.
Use a mild dishwashing liquid or Castille Soap. Natural Hand soap can be used too. Add 1 tsp of dishwashing liquid soap to 1 Litre of water. Place in a spray bottle and gently spits your houseplant, covering the top and bottom of the leaves.
Control Insects
You can use a diluted solution of vinegar to eliminate harmful insects in the garden, but avoid using full-strength vinegar so that you don't accidentally harm good garden plants. Create a solution of equal parts vinegar and water and spray it around problem areas in your yard.
A stiff spray of water is surprisingly effective at killing and/or knocking soft-bodied bugs like aphids and spider mites off of plants.
Prevent Fungal Disease
MAKE IT: Mix 1 teaspoon of baking soda and 2-3 drops of liquid soap in 1 liter of water. Spray the solution on the infected plants. Baking soda helps the plants become less acidic and prevents fungal growth.
If you're spraying or watering the soil for fungus, eggs or larvae, be certain you really soak the soil. If you have any of these problems, you can use hydrogen peroxide on your plants once a week.