Treatment Planner
Fungus Gnats Treatment Plan
Why one treatment never works: The adults you see flying are the harmless half of the problem. The larvae live in the top two inches of soil, and the full egg-to-adult cycle takes about three weeks in warm indoor conditions. Swatting adults or hanging a trap does nothing to the generation already in the soil, so the plan has to run long enough to outlast every egg that was laid before you started.
How bad is it?
Gnats visible around several plants, sticky traps filling within a day or two.
Expect this to take 3–4 weeks
Day 1
TodayStop egg-laying and start killing larvae.
Check for: Traps start catching adults within 24 hours. That is expected — a rising catch count now is a sign the traps are working, not that things are worsening.
Week 1
Days 2–7Keep the soil hostile while the first eggs hatch.
Check for: Adult numbers on the traps should peak somewhere this week and then begin to fall. Soil surface should be visibly drier between waterings.
Week 2
Days 8–14Catch the wave hatching from eggs laid before you started.
Check for: Trap catches clearly declining. You should see few or no gnats rise when you water.
Week 3+
Days 15–21Confirm the cycle is broken.
Check for: Zero new adults on fresh traps for seven straight days means the infestation is broken.
Still not working?
Still catching adults after four weeks? The usual cause is a reservoir you haven't treated — an untreated plant in the same room, a saucer holding standing water, or a bag of potting mix that arrived infested. Treat every pot in the room simultaneously, discard standing water, and store opened potting mix sealed and dry.
Read the full fungus gnats guide →Other treatment plans
Not certain this is what you have?
Use the diagnosis tool first →Get seasonal plant care reminders and pest alerts.