Conquering fungus gnats

[ameno]

Every year I have severe infestations of fungus gnats in my conservatory (where I raise all my veg plants). Last year I lost quite a few squash and cucumber plants to them.
But this year I seem to have hit upon a successful method of keeping them away: I top my vulnerable pots with a mulch of garden soil. It has been a complete success, with no larvae in any of my cucurbits, despite there being lots of gnats in the conservatory.
Fungus gnat larvae might do severe damage to certain plants, but the adults don't target the plants. What they are after to lay their eggs in is decomposing organic matter (that is, the compost). By topping the compost with a continuous inorganic mulch it deters the gnats from laying their eggs there (it probably wouldn't work if your soil is particularly high in organic matter).

My pepper plants got damaged by them this year, too (didn't even know the larvae ate pepper roots, as they don't eat all plant roots. For instance my tomatoes, sweet potatoes and beans never seem to get damaged by them, despite there being larvae in the pots). So from next year I shall probably mulch those, too.

[mothhawk]

Good tip, Ameno, thanks.

[Bren In Pots]

Thanks Ameno i'll give that a go, I've had fungus gnats problems with early windowsill grown plants..

[Jungle Jane]

I used to get fungus gnats but for years now I water from below on trays & it stops the top of the compost getting wet,that’s where they lay their eggs.