Ok,so first year rooting indoors and I am pretty sure some of the small summer rooted fig trees i brought in from the mini greenhouse have brought gnats in with them,I've seen some now,squashed a few but I know it's the larvae that do the damage,and I have started to loose some of my up-potted cuttings,even lost 2 well rooted summer cuttings that never went dormant,one day they are fine,then they wilt,and then they are done,when I pull them up the roots are in a state,not rotted but just gone.

I've been careful not to over water or under water after making that mistake in round 1,now I'm starting to loose the survivors as well and want to sort this now before I loose any more.

I'm pretty sure it's the gnats and I'm gonna kill the buggers.I have heard folks here say they use dilute Hydrogen Peroxid but the instructions are a bit vague from what I've read.

I have 6% HP from the pharmacist(lowest % they had),they questions I have if you use it:

1,What % HP do you use?
2,how many parts water to HP?,or what Mil water to what Mil HP?
3,water as normal?, water it enough to drain right through?
4,should the mix be dry before you do it or doesn't it matter?
5, spray the leaves/cutting as well?
6,repeat application?,if so how often?

Any other thoughts t advice would be welcome,I'm going to war

I've been struggling with this as well. At first using Diamotomaciois earth seemed to work but they just came back. Frustrated, about 5 days ago I used what I heard was the recommended ratio of hydrogen peroxide. That being 1 part H2O2 to 4 parts water. I haven't seen them since but if they return I'm going to hit them with undiluted 3%. I get the 3% at the local dollar store.

I completely soaked the mix given this is only supposed to work by killing the larva on contact. So you've got to get it everywhere. Of course the down side is that you risk overwatering.....I made sure I shook as much liquid as I could after watering. I also didn't cover the cuttings so it would evaporate faster. If you have a dryer area to place them in all the better.

I made sure to get it on the leaves and stem as well.

Don't know how long to wait before re-applying. I suppose if they come back.

I haven't lost a plant to this yet. Just saw the bugs and took action

I don't measure ratios, I just make sure it is very dilute. I pour about 0.5cm of 3% peroxide to the bottom of an Ikea spray bottle, then fill up with tap water. I sprayed the top of the soil on cuttings that have gnats buzzing around them, or all cups when I wasn't sure which one was the source. Make sure not to spray too much or don't forget about it when watering. I hunted and killed all gnats in about 2 weeks, so I can confirm that the method works. In turn I just managed to overwater one and the roots rotted, now trying to revive it.

I use hydrogen peroxide in my cloner every three days as it will not build up. Keeps everything clean and fungus free.

check this out   http://everything2.com/title/fungus+gnat

Dave that sounds much safer than gnatrol.
Will be trying out.
Nice part of using a closet, fungus gnats stay inside it.
But I have seen the critters again this year.
Thanks Dave

Doug

can you spray the cutting leaves with this 1 to 4 ratio?

Gnat Vac still sweeping those suckers up 24/7 for about $1.70 a month. Obviously I have some but almost never "see" them. Cleaned it last week.

Grinds em up with a fan?
Suitable death for the critters.
But it wont kill larvae.
Doug

sweet
I like your get er done approach and construction.
That plus the hydrogen peroxide for the larvae shoud
get good control of the gnats. I'm gonna build me one for the fun of it.
Are gnats attracted to your cool white flood light led?
Not the light in the box.
Doug

Got he bugs eh?
Very common.

Doug

I'm curious. Does anyone know why gnats don't pose a problem for plants outdoors - in ground or potted? The only growers who seem to complain are those rooting indoors. Obviously they wouldn't be as annoying outside but why are they not eating the roots on all our trees the rest of the year? Or if I were rooting outdoors in spring? ( which it seems most do)

KK,I love the gnat mincer/dessicator,they get what they deserve, I've not had enough to need anything like that, the flying ones are slow and they don't make it far,it's their offspring I am worried about.

Thanks for all the responses,so the consensus is this stuff works.

Ive now tried the HP on about 75% of my up potted fig trees,including the summer rooted ones I've brought in doors.Then I ran out of HP,I'll have to try and buy some more tomorrow((it's a national holiday)hopefully this will do the job.What I loved about the HP is the fizzing!, I can just imagine what it's doing to the fungus gnats lol,burn you little shi*s burn.

The more opinions I've read the more it seems that 4-1 of 3% is the chosen magic number.TorontoJoe you are the consensus candidate lol.Glad it has worked for you and Pverdes.I will give spraying the leaves a try as well,I could only get 200ml from the pharmacist so will go buy a couple more bottles to make sure I do full gnat coverage.

I used a 5-1 solution of the 6%(recommended for children and the elderly according to the bottle),hasn't harmed the plants yet lol.I might try a weaker solution of the cuttings still in the rooting cups as I imagine they are more sensitive to this sort of thing(and also to that volume of water).

So in answer to my questions st the top off he thread and in summary:

1,What % HP do you use?
Answer: 3%(though other strengths are avaliable,adjust accordingly)
2,how many parts water to HP?,or what Mil water to what Mil HP?
Answer:4 parts water 1 part HP for 3% HP. Solution,adjust according to HP strength
3,water as normal?, water it enough to drain right through?
Answer:Soak through,kills on contact so need to get them all
4,should the mix be dry before you do it or doesn't it matter?
Answer:Not essential but dry soil helps combat the gnats and it will help in avoiding over watering
5, spray the leaves/cutting as well?
Answer:Yes
6,repeat application?,if so how often?
Answer:Yes if,and as and whenever needed

the link did say
"1 part hydrogen peroxide (H2O2) solution with 4 parts water. Use 3% solution,"
Your mix sounds much stronger.

Doug

This just in. I got home from work tonight and noticed a gnat. I was furious! I soaked everything just days ago. Then  I watched as it did a nose dive and guess where it went? Straight to one of the trays to a drain hole. I took a plate with some of the H2O2 mix and dipped the bottom of all the pots just deep enough to cover the holes so it would soak just a bit in...Not long enough to soak in to much...They've already had enough water. Then I put some in a spray bottle and gave a mist to the outside of the pots as well as the trays.

There's no emoji to express how I feel about gnats...

So the message is, "protect all points of entry"!

Doug yes,solution is stronger,why? 1, they only had 6 and 9 % and 2, I'm crap at maths,I realise now 1 to 8 would have been right,what the hell,as long as it kills the gnats

I have been using H2O2 for years for gnat control. It also kills nematodes. I cut the 3% H2O2 in half with water but 4:1 sounds just as good and keeps the expense down. The molecule of oxygen that is released benefits the roots of the plants. You may have to repeat dredging the pots two weeks after the initial treatment. The other thing I do to keep gnats out is I use pieces of plastic bags, the kind used for groceries, and place on top of the soil around the cutting or the plant. It acts as a barrier and also serves as a mulch to keep the soil from drying out too quickly. The plastic is also very thin so it is quite pliable and won't damage the plant.

haslamhulme, I don't know if more is better in this case.
I'm going to follow the directions of those that have already
tested it. Then I will see if it works.

Doug

@TorontoJoe Words cannot fully convey the level of hatred i have for fungus gnats... To give you an idea of how tough they can be here's this: I had a number of 32oz cups that I set up to root some nice cuttings. I put 1.5" of perlite in the bottom of the 32oz container that has numerous bottom holes as well as numerous aeration holes all around at various heights... I put in a lite rooting mix as recommended by the folks on this form and then after putting the cutting into the mix, I topped it all off with an inch of perlite. I then take an extra large coffee filter and put it into the bottom of another 32 oz container and put the rooted cutting container into the one with the filter such that the filter surrounds the bottom of the cutting container leaving a small 1" gap between the 2 containers to catch and liquid flowing down from the rooted cutting. In the classic 3 cup method, I then topped the rooted  cutting contained with another 32oz to act as a humidity bin. the top has several air holes to allow for some humidity to escape.

Well, the other day I was checking the cups to look for roots and what do i see? Fungus gnats had gotten in between the two cups and had actually drilled through the damp coffee filter and into the bottom of the rooting cup. I don't think they made it past the 1.5" of perlite in the bottom of container but looking closely, it was evident that they at least tried... There was no liquid in the gap between the two containers but there were numerous gnat bodies laying there... I was shocked as I had not thought that the gnats would find their way into the bottom container and try to go in from the bottom... I replaced the filter with a fresh one and haven't seen any evidence of a new attach but I remain vigilant... By the way... I have been watering exclusively with a gnatrol mix but now have upped the firepower and am using a sample of Riptide sent to me by a generous forum member....

Many have given up on winter rooting altogether because of gnats. It brings me back to what I mentioned above...

Does everyone who roots indoors have this problem? Or is just a small percentage of us who got something wrong? Or tainted mix?

And why are our outdoor plants not getting ravaged all summer?

I agree with you Doug,more might not be better,if it's as affective at half the dose that's half the cost as well,it doesn't seem to have hurt the plants,but I'll be switching to a 1 to 8 solution of 6% next time in the absense of 3% here.

I may look at using a cloner next season and see if that helps,it won't if I bring the gnats in with the mix though.TorontoJoe,I also never had this problem summer rooting outsid,it seems these gnats love indoors,but I'm pretty sure they got in to my summer rooted plants from a fig tree I bought in,just shows you have to be careful with stuff coming from outside

I don't suggest you do as I do, but I got out the old handy 7 dust.
It says right on the bag, fungus gnats.
I dusted the potted plants in my closet last night.
Today, I have maybe 4 or 5 gnats I seen flying around.
Even a sticky fly trap would help if you have a bunch of gnats flying around.
I will never forget finding a fungus gnat at the bottom of my coffee cup.
No more, ever again. Yuk.
Joe, try the search function,, google or here.
There is all the information you need if you look for it.

Doug

I'll check it out. Thanks

I get gnats, but the hydrogen peroxide worked for me. Maybe because now I just add it from the start? I don't ever see any, anymore. Also a note is the peroxide just kills eggs, any that hatched, are still going to be around for a bit.
Hydrogen peroxide soon loses it's killing power. You need to water from the top down. Only mix what you plan to use, you cannot store it mixed. Also a chance the bottle one buys is just water, test the stuff, make sure it bubbles.

In the home brew market they make a powdered version that is slow release. You add it to distilled water. In order to ferment, you need everything else dead, and the home brew companies suggest using hydrogen peroxide in the form they sell. I thought though this slow release form might be extremely useful to gardeners too. It would be a great way to clean old containers for example.  The home brew market cleans all equipment this way too. It would be a good way to stop the spread of any plant diseases, not just gnats.  Using bleach is far from ideal. Such a corrosive product I myself would rather avoid. What happens with me, is I just don't clean the pots, I might with peroxide, as it's not harsh to me in any way.