Plant problem guides

Houseplant troubleshooting

How to get fungus gnats under control indoors

Fungus gnats thrive in damp organic potting mix. Control works best when you combine drying the top layer, catching adults, and interrupting larvae in the soil.

First clueTiny dark flies around pots
Often tied toTop layer staying wet
Before treatingCheck soil, roots, light, and recent changes
Fungus Gnats plant problem guide

What You May See

Look at the whole plant before deciding on a fix. The age of the affected leaves, whether the soil is wet or dry, and how quickly the symptom appeared all help separate normal adjustment from an active care problem.

  • Tiny dark flies around pots
  • Gnats lifting from soil when watered
  • Larvae in consistently damp mix
  • Seedlings or small cuttings weakening

Visual Checks

Compare this symptom image with the affected leaves, roots, soil surface, or growth pattern on your plant. Use it as a visual reference, then confirm the cause with the checks below before changing care.

Fungus Gnats diagnostic example Fungus Gnats exampleUse this as the main visual reference for the symptom pattern.

Likely Causes

Match the symptom to the plant's recent care history. The same leaf problem can come from different causes, especially when light, soil moisture, temperature, repotting, and fertilizer changed around the same time.

CheckTop layer staying wet
CheckFrequent small watering
CheckOrganic debris on soil surface
CheckNew bagged soil carrying larvae
CheckCrowded plant shelves with slow airflow

First Checks

Do these checks before buying treatments or repotting. A few minutes of inspection can prevent the common mistake of watering a plant with damaged roots, fertilizing a stressed plant, or moving a low-light plant straight into harsh sun.

  1. Check which pots stay damp longest.
  2. Look for algae, fallen leaves, or decomposing material on the soil.
  3. Use yellow sticky cards to identify active pots.
  4. Review whether watering is shallow and frequent.

What To Do Next

Choose the step that matches what you confirmed. If more than one cause seems possible, start with the least disruptive correction and watch new growth, root condition, and drying time for signs of recovery.

  1. Let the top layer dry more between waterings where the plant allows it.
  2. Remove debris from the soil surface.
  3. Use sticky traps for adults while treating the soil stage.
  4. Consider bottom watering temporarily for plants that tolerate it.

What To Avoid

  • Do not spray only the flying adults and ignore larvae.
  • Do not keep all plants wet because one plant is thirsty.
  • Do not reuse infested wet soil for fresh cuttings.

Related Guides

How to Get Rid of Fungus Gnats How Often to Water Houseplants