Hi everyone! This is my first post on the forums here, which I recently discovered. I look forward to getting to know everyone!

According to the OP, adding "a few drops to your water" will get rid of fungus gnats in your house plants. I want to give this a try, but I'd like to be sure I put in the right amount. Does anyone know if this works and how much peroxide to use in how much water? How much water do you add to the plant? Do you use it every time you water? How does it work? Does it kill them or just repel them? What affect could it have on the plants?
I have a number of pots on my window sill, including 3 miniature orange trees (calamondins), and the soil is just crawling with fungus gnats. I have tried making sure the soil dries out really well between waterings, but the plants always start dropping leaves (presumably from drying out) before the fungus gnats go away, and they come back in full force as soon as I water.
I have been putting pieces of BT mosquito dunks in my watering can, in the tray below the plants, and even crumbled over the soil, as I've heard that this should keep them from developing past the larval stage, but it doesn't seem to be working. The gnats are all over the house and driving us crazy!
Some of them were coming from one of my worm bins, and I've moved that back outside now that it has warmed up a bit, but again, the soil in my pots is still seething with the little buggers.
Anyone have any pointers?

Hi Joel,

I'd take those plants outside, remove them from their pots, and dunk each rootball into a five gallon bucket of water. Rinse and rinse until nearly all the soil is gone and only roots remain. Then clean the pot off really well and repot the whole thing in brand new potting soil.

Thanks Dave,

I'm a bit hesitant to do that with the orange trees, as they are somewhat sensitive and aren't fond of being repotted too often. I did repot them all a month or so ago, but I left most of the soil around the roots. I didn't see any evidence of root rot when I did this, but the leaves have been curling and emerging twisty and deformed.
I'm also hesitant to bring them outside yet, since it's still pretty cold here and they're sensitive to drastic temp changes. But I'm hoping they'll bounce back once it's warm enough for me to bring them back outside and in full sun again.
Any more thoughts?

Well I was thinking the yellow sticky traps might help with the adult flying gnats
and I have read that a liberal sprinkling of cinnamon on the soil , but have not tried it. I would think the cinnamon would not hurt anything and is cheep and easy

Good luck and let us know when you find a cure

Oh yea to ATP

Well now they're spicy and mad. I'll let you know if that keeps them at bay. If not, peroxide is next at bat.

Well, I've now tried both the cinnamon and the hydrogen peroxide solution, as well as a misting of my diluted orange peel vinegar. Their numbers seem to be down a bit, but they definitely haven't left. Any more ideas out there?

Stardate: 03192014
Fungus gnat mayhem continues unabated. Morale is low. This may be my last entry.

Live long and prosper.

Do you fertilize with something organic? That might encourage fungus, yeast, or something else that gnats like. Maybe try a different fertilizer for a few weeks.

Is the soil highly organic? Maybe the top layer needs to be less organic.

Maybe a dry soil SURFACE would help discourage the gnats.

Bottom watering might help keep the surface dry.
A small fan?
Or less frequent, heavier waterings.
A 1/4" or 1/2" layer of coarse grit or very very fine gravel on top of the soil mix would dry out quickly.

I like shredded pine bark nuggets or chips as a top dressing. Since it would only be a top dressing, the chips or nuggets could be almost any convenient size larger than 1/8" or 1/4". The nuggets have to be big enough that they don't hold much water by capillary attraction. Thus you would have to screen out or blow away powder, dust and fine bark fibers.
Some nuggets should be small enough that gnats can't easily crawl between bark chunks and reach a damp, organic soil surface.

P.S. .... H2O2 dilution

http://www.using-hydrogen-pero...

This site suggests 0.1% hydrogen peroxide for watering plants or soaking seeds.
Use 1-2 ounces per quart, if you have standard "drugstore peroxide" that is 3% strong.
("Food grade" peroxide is 35%.)

I have read several experienced gardeners saying they use stronger concentrations.

I have gone round and round with fungus gnats, too! I mean they just come out of no where! I hate hanging those ugly sticky strips in the bathroom. I think I will try the h. peroxide that Careyana suggested. I also found this article that said to use vinegar. Has anyone besides Josephus used vinegar? It says to put some apple vinegar in a jar. Well at any rate, here is that link. It's worth a try. http://evonhall.hubpages.com/h...

I have used the vinegar for years , and yes it does work , but like other attractants it also attracts the flies. However there is some satisfaction seeing them drown in their own gluttony.