---
title: "Hello! I’ve had an issue with fungus gnats and I think it’s the soil…"
description: "Hello! I’ve had an issue with fungus gnats and I think it’s the soil I’ve been buying since they keep coming back after I repot plants. How do you know you’re…"
url: "https://getplanta.com/community/lKxUkhzRR_aIJD7o1QvtwQ/ZZJw3PcYkIDmXaTVTKTdBT?language=ja"
community: "Pests, diseases and problems"
author: "Jessica"
published: "2025-04-30T03:52:16.547983Z"
language: "en"
image: "https://images.getplanta.com/v2/cloudinary/global_data/communities/pestsDiseasesAndProblems.jpg"
---

[コミュニティ](https://getplanta.com/community.md?language=ja) / [Pests, diseases and problems](https://getplanta.com/community/lKxUkhzRR_aIJD7o1QvtwQ.md?language=ja)

# Hello! I’ve had an issue with fungus gnats and I think it’s the soil…

_Jessicaさんが2025-04-30に投稿しました_

Hello! I’ve had an issue with fungus gnats and I think it’s the soil I’ve been buying since they keep coming back after I repot plants. How do you know you’re buying soil from a good source and anything you recommend doing to treat the soil before potting to make sure there aren’t any gnat eggs in it? Thank you!

## 8件のコメント

### Daniiさんが2025-04-30にコメントしました

A method to treat soil for possible pests is to pour boiling water over it while in a well draining container/pot.

#### Gaileen Joyさんが2025-04-30に返信しました

NOT while the plant is in the soil though!!

### Sapphireさんが2025-04-30にコメントしました

Neem oil or castille soap mixed with water can take care of the adults, then to get eggs and larvae you can use BTI treatment or mosquito bits. There are also certain powders that you can sprinkle on your plant that causes the fungus gnats to meet their maker if they try to invade.

### Lukeさんが2025-04-30にコメントしました

Nematodes worked for me

#### Anne Marieさんが2025-04-30に返信しました

I second this! Practically eliminated my problem

#### Jessicaさんが2025-04-30に返信しました

Is this safe around animals? And what’s your preferred brand for indoor plants?

### KJMさんが2025-04-30にコメントしました

I would not be too critical of your soil company. It would be quite impossible for them to ensure that you never get gnats. Some gnat will come along and lay eggs in your soil regardless of how clean it was when you got it. Adult gnats are not harmful to your plant. The larva can do damage to the roots. They're just very annoying to you. Use yellow sticky traps to entrap the adults and treat the soil with mosquito bites or other treatment for mosquitoes. Some people make a tea from the mosquito bites and watered in others crumble up the product and scritch it into the top inch or so of soil. This will work to kill the larvae. Neem will also work as a suffocant. Either way you want to attack life cycle from both ends adult and larva.

### Sunnyさんが2025-04-30にコメントしました

All soil can get fungus gnats if the conditions are right such as overwatering. The adults fly around and can come back to lay eggs even after you replace the soil with a brand new bag. Let the soil dry out. Treat with Mosquito Bits and use yellow stickies to trap the adults until all the larvae are dead. Continue to water with Mosquito Bits every time.

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