Solving Mold and Fungus Gnats in Self-Watering Pots

Mold on soil and tiny flies (fungus gnats) in Kalanchoe and Coleus plants in self-watering pots indicate chronic overwatering. The wick system keeps peat-heavy soil constantly saturated, creating anaerobic conditions that rot roots, breed gnats, and promote mold.

Immediate Fixes

• Cut the wick in half or remove it entirely to reduce water uptake.
• Amend soil with extra perlite (for aeration) and horticultural charcoal (to reduce acidity).
• Allow soil to dry thoroughly between waterings—top 1–2 inches dry.

Long-Term Solution

Self-watering pots suit only moisture-loving plants (e.g., ferns, peace lilies). For most houseplants, use standard pots with drainage holes. Keep plants in their nursery pots inside decorative cachepots—this allows excess water removal and salt leaching.

Gnat Control

Dry soil breaks the gnat lifecycle. Yellow sticky traps catch adults. A soil drench with Bacillus thuringiensis israelensis (BTi) kills larvae safely.