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Pests
Fungus Gnats in Fern Potting Mix
Commonly affects: Various ferns (Polypodiopsida)
Small dark flies hover around the plant and soil surface, thriving in the consistently moist conditions ferns are typically kept in.
Potential Causes
- 1Consistently moist potting medium, which ferns need but which also favours fungus gnat breeding
- 2Organic matter in the mix breaking down and attracting egg-laying adults
Solution Steps
- 1Use yellow sticky traps to catch and monitor adult gnats without needing to dry the soil excessively
- 2Apply a BTI product to the soil to target larvae without harming the fern or requiring drier conditions
- 3Let the very top layer of soil dry slightly between waterings if the fern's specific needs allow some tolerance
- 4Avoid letting water sit in a saucer beneath the pot
Prevention Tip
Since ferns genuinely need consistently moist soil, use BTI larvicide rather than drying the soil out to control fungus gnats.
