Florli

Plant problems

Fungus gnats in potting soil

Adult gnats are mainly a nuisance, while heavy larval populations can affect young or weak roots.

Moist mix

Constantly damp organic soil supports larvae.

Organic debris

Decaying material provides food.

Spread

Adults move easily between nearby pots.

Problem

What to do next

  1. 1

    Allow appropriate surface drying for the plant.

  2. 2

    Remove debris and correct drainage or watering frequency.

  3. 3

    Use monitoring traps for adults and a labelled larval control if needed.

Observation

When to act sooner

  • Seedlings or cuttings begin to collapse.
  • Large numbers emerge from several pots.
  • The plant also shows signs of root rot.
Important

Fungus gnats in potting soil can have several causes. Confirm the plant, conditions and recent care before choosing a treatment.

Florli

Related guides and features

Library Plant problems Yellow leaves, brown spots and root problems: learn what to inspect first and how to avoid making the situation worse. Read the guide → Feature Plant problem checker Florli helps you organize symptoms, consider possible causes and choose a cautious next step without presenting an uncertain result as a definite diagnosis. Read the guide → Feature Plant and garden journal Record watering, feeding, mowing, planting, pruning and your own notes in a history attached to the right plant or place. Read the guide →
Sources and further reading: University of Maryland Extension: houseplant pests

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Prepared by Florli. This is general guidance. Sources are listed with each guide, and every decision should reflect the species, location, weather and the plant’s current condition.