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Gnats on Houseplants

Category Pest Control
Gnats are a nuisance, especially when your house plants are covered in them. Get tips on getting rid of gnats on houseplants in this guide.
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March 29, 20090 found this helpful

Question:

I recently purchased four beautiful Massangeana Cane plants from Lowe's and some good potting soil. I potted my plants in nice planters and within a week there are millions of gnats crawling out of the soil and flying everywhere. Is there anything I can do to get rid of these pests?
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Madi from Oceanside, CA

Answer:

Almost everyone who grows houseplants has experienced these little black gnats. They are called fungus gnats. They inhabit the fungus and decaying plant material found at the base of houseplants. The fungus gnat's lifespan is as follows:

Adults live about 7 to 10 days and deposit eggs on or in moist soil. The females lay from 100 to 300 eggs in batches of 2 to 30 each in soil containing decaying organic matter. The eggs hatch in 4 to 6 days and the larvae feed for 12 to 14 days. The pupal stage is about 5 to 6 days before adults emerge. Repeat.

The adult gnats are an annoyance, but they won't hurt your plants. The larvae, however, can damage the feeder roots and root hair causing a general loss of vigor to some plants.

The best way to prevent fungus gnats is to use a sterile potting soil mix when re-potting (one that is free of bark chips) and to make sure your pots have good drainage. These guys need a moist environment to feed and continue breeding. So if possible, it's a good idea to let the surface of the soil dry out as much as you can (without injuring the plants) between watering. This works well to kill the larvae.

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Here are some other things to try:

  • Be sure to practice good sanitation by removing any dead plant material and debris from the base of your new plants.

  • Replace the top few inches of soil with a sterilized potting mix.

  • Place yellow sticky traps near your plants to monitor the population and nab flying adults.

  • Use a fine peat moss on top of your potting soil to deter the gnats.

  • Place 1/2 inch slices of raw potato on the surface of the soil and discard (along with the larvae) after 2 days. Repeat until larvae are gone.

  • Place red cooking wine or fruit juice in glass and leave it out by your plants. Adults will dive in and drown.

Ellen

More Answers

Lemon Scented Spray

Use any type of lemon scented spray. I use lemon scented ammonia. Wipe down the area with the lemon scented ammonia or spray the area. You will notice there are very little or no gnats at all instantly.
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By tonyaphl

Soap and Water

I just mix up some soap water in a spray bottle to get rid of the gnats.

By Joyce

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Questions

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By 0 found this helpful
September 13, 2010

I would like to know how to get rid of small flies in house plants?

Hardiness Zone: 8b

By Ingrid from Plano, TX

Answers

February 10, 20110 found this helpful
Best Answer

When I bring my plants indoors in late fall, I group them under lights, in a cool room in the basement. I than fill 3 or 4 empty margarine containers with water and space them around the plants on the table. I water the plants very sparingly all winter.

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These pesky creatures love water. These margarine containers become their source of water, where they congregate and drown. Keep the containers filled with water to the very top at all times.

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By 0 found this helpful
July 29, 2011

My mom told me to mix water, dish soap and lemon juice into a spray bottle and spray my plant's leaves, top and bottom, and also water them with this mixture to get rid of gnats and/or fruit spiders. I love my plants and many of them are too large or have very long vines to re-pot them to help solve the problem since both my husband and I both have seriously bad back problems.

Do you think it will hurt my plants? I love my plants, each one has either been a present from my husband on a special occasion or gifts from our daughter on mother's day or birthdays so to lose one would feel almost unbearable. Please tell me if this will work, I am hoping it will as we are also Retired Air Force and money is tight. Thanks for helping and God Bless.

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By MoonLitBelle from Las Vegas, NV

Answers

August 4, 20110 found this helpful
Best Answer

Make sure that your dish soap is one of the very mildest-in other words, don't use anything marked 'concentrated grease relief', or as containing bleach or OxyClean type stuff.

Ivory dishwashing soap was the best thing, we Master Gardeners (university extension service training, repaid by doing volunteer work in the community) used it for years as a safe pesticide (mixed with water) but then the company changed it's formula, and now I'm not sure if it's still safe.

If your soap is VERY mild, go ahead and try the homemade pesticide on a weed, lol, and see what happens. If it's still alive in four or five days you are probably safe to try the home mix on your more precious plants.

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By 0 found this helpful
July 29, 2011

I have gnats on my indoor ivy and have been spraying it with insecticidal soap, but I found one on the top of my coffeemaker. Is there any homemade ways to get rid of the darn things?

By Holly from Lancaster, Wi

Answers

August 4, 20110 found this helpful

Are you absolutely sure the gnats are from the plant? Sometimes what looks like fungus gnats come in through the drains, not the plants.

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July 20, 20100 found this helpful

How do I get rid of little bugs that look like fruit flies in my houseplants?

By Mitch88 from Ontario, Canada

Answers:

Gnats on Houseplants

This trick worked overnight! I work in an office and a coworker just brought in a newly potted plant. When she was watering it she noticed these pesky gnats and I told her to mix a drop of lemon essential oil and a drop of lemongrass essential oil and rub it around the lip of the pot. Voila! No more gnats! (07/30/2009)

By Virgogo

Gnats on Houseplants

Forget most, if not all, of the suggestions here and on other sites. I tried them all (soap, lemon, beer, vinegar, sand) on my house plants. The lemon one is particularly silly. I think they actually love it.

Now for what will work and it's very simple: Insect repellent wipes, i.e., mosquitoes, etc. The ones that come in those little packages.

Wipe the edges of your plant's pot and then for added benefit, leave the wipe for awhile under the plant itself (if the pot's big enough). They hate it and were gone almost immediately, never to return. (02/28/2010)

By ztrenholm

Gnats on Houseplants

OK, forget everything you just read! The only way to get rid of (and by "get rid of" I mean kill them!) gnats from your houseplants is to kill the source of their food, which is fungus. Most remedies posted here will move them from one plant to a different food source only to return a day later. For the past several weeks, I've been inundated with tons of gnats from several houseplants that I purchased at the big box store. It's just inevitable. I've tried Windex. I've tried vinegar and orange juice with a shot of oil. I've tried drowning my plants overnight in a tub of water. I've tried skimming and baking the top three inches of the plant soil. I've tried spraying the plants with plant-based Raid. None of them work!

Finally, I went to Walmart and got Garden Safe Fungicide, which is sold in the outdoor garden area, not inside the store with the RAID and other pest control products. It worked in one day! I went from millions of little gnats buzzing around my eyes, trying to get up my nose and simply disrupting my life on a minute-by-minute basis, to having not a single gnat in my house overnight! Spray the fungicide liberally on the top soil of the plant, and on the leaves (both sides) until it runs off the leaves a bit and on the stems.

For an added bonus, spray the air, the area around trash cans, litter boxes, sink drains and even the overflow opening of your bathroom sink. Anywhere they might find a source of food. It works! (03/13/2010)

By pornstar40

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July 21, 20090 found this helpful

How do I get rid of gnats on house plants?

By MonicaC. from Harlingen, TX

Answers:

Gnats on Houseplants

The first thing I do is remove the soil from the plant and wash the roots very well with dishsoap and water. I wipe down the leaves as well with same solution, but make sure all soap is rinsed off. Get some new soil and repot your plant.

Normally I like to do this outdoors to all my plants, because if one is infested, all are. Just leave the used soil in your garden or spread on your lawn. No need to toss it when it can be put to use in your outdoor garden.

Karyn (04/01/2009)

By Karyn01

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June 30, 20080 found this helpful

I recently purchased four beautiful Massangeana Cane plants from Lowe's and some good potting soil. I potted my plants in nice planters and within a week there are millions of gnats crawling out of the soil and flying everywhere. I just purchased Knock-Out Gnat from Gardensalive.com and waiting for its arrival. Hopefully it works but in the meantime, is there anything I can do to get rid of these pests?

Madi from Oceanside, CA

Answers:

Gnats on Houseplants

Set out some apple cider vinegar in a bowl, with 1/2 teaspoon of vegetable oil, and a piece of apple or a banana peel and let it set out. This will surely works. You can try setting out about 3 or 4 bowls of this. Since the source is coming from your house plant you need to change soil, rinse plant off, re-pot and place sand over the top of the soil. (06/28/2008)

By Dee

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June 26, 20080 found this helpful

I have problems with gnats (I think that is what they are). I've noticed them throughout the house and they are coming from my plants. What can I do to get rid of them. Should I re-pot them? Thanks for any suggestions.

Hardiness Zone: 4b

Marsha from Norfolk, NE

Answers:

Gnats on Houseplants

Believe it or not I have read that a cat box can attract them and is a perfect breeding ground for them. So do you have a cat? Perhaps that is the drawing card to the gnats? (10/25/2007)

Nasty Gnats on Houseplants

I used a commercial insecticide called Wilson's Fungus Gnat Spray. Used it once spraying only the soil. Seems to work like a charm.

This insecticide has me a bit worried though. If it's that strong, what's it doing to me?

(01/29/2008)

By Fungus Gnat FRee

Gnats on Houseplants

I have found 3 sources for the Gnats/fruit flies. 1. They come up through the drains from the sewers and lay their eggs in the vent in bathroom sinks. 2. their eggs come in with new plants or potting soil purchased at garden or any store that sells either. In Western New York we have to bring in certain plants for the winter.I raise some exotic plants that go dormant and then in Spring we revive them when they come in there are always Gnat eggs in the soil.

The vinegar in a water bottle with a paper funnel will eliminate many of them, but the problem is that they lay eggs before capture and will still thrive. It really just "lessons" their numbers. Cut garlic works at keeping them aways from things (damp soil/fruit) where they will lay eggs. Someone told me to try fresh orange peels, but I haven't tried it yet. The smell will attract them but the oil in the peel will kill the eggs. You have to make sure there is no fruit on the peel at all-so they said.

With potting soil for the indoor gardener-you have to bake it in the oven. I dump the bag or part of it-depending on the size into a large stainless steel bowl and bake it at 200 degrees for 30-45 min stirring it 1 or 2 X's. This ALWAYS works. Store bought soil will 100% of the time have eggs in it unless it is labeled sterilized.

The drain is the easiest-take some shaving cream or hair foam and spray it into the little vent hole in the top part of your sink while the drain is closed. This is a famous little hive for them. It is damp and only air passes through it. The tub really never gives them time without running water to get their eggs lain and hatched.

When bringing plants indoors for the winter I use a modest windex on the plant and soil. It also contains ammonia which can benefit green plants. It isn't something to do on a continuous basis. It is mild, doesn't harm any plant I've done it to and always eliminated the bugs. You may want to try it on a plant you're not greatly attached to-I wouldn't want to be responsible for any losses. As you might have guessed by now, I have been dealing with these "brats" for years-I haven't won the war, but I am staying a little bit ahead of them---finally! Thanks!
Tim (03/13/2008)

By tclancy

Gnats on Houseplants

Mix in about a Tablespoon of joy lemon dishsoap when watering. (so far it hasn't hurt my plants and I've been doing it for about 3 months.) It does the trick. I have seen maybe one or two flies but that's better than 30 sometimes in one day. Try the dish soap it really works. I have fungus flies... not fruit flies though, don't know if that matters. (03/30/2008)

By brenda

Gnats on Houseplants

Sand doesn't work. Don't waste your time and money. You can take the plants outside and scoop some of the top layer of soil off. That gets rid of some of the adults and eggs. I use fly strips to catch the flying adults and I also cut those gluey mouse traps and put them in and around the plants to catch the little B******S!!I have tried all of these measures posted here with no luck, (except throwing the top layer off, it does help.) I am currently trying Plant Gel I got off the internet from a place called DNB Designs in Colorado Springs, Co.

I don't know if it will solve my gnat problem or not. I just re-potted them today. Time will tell. (It may be food to them, Ha!) I have already ridded my plants of quite a few of them by scooping that layer off. Anyway, good luck to all and if anyone figures it out please, do tell! Thanks. (04/18/2008)

By moonbeampm

Gnats on Houseplants

I had gnats in all of my houseplants for a year. I found Garden Safe Fruit and Vegetable insect killer at wal-mart. It works. I have not seen any more gnats. It's very safe since you use on fruit and vegtables. (04/23/2008)

By sue

Gnats on Houseplants

I was told to use bleach in the drains at night. I put it in all the drains and it seemed to help. It didn't take care of all of them, but it sure did help a bunch! I'm going to try the soapy water and maybe the vinegar/lemon juice. Thanks for all the good ideas. (05/18/2008)

By Yellow Rose

Gnats on Houseplants

Use Dry Sand (not salty sand from beach!) and Cover only the top of the soil. When the Weather is nice, open the window to refresh the air very well. And about adult flies,
they doesn't live for long time. They will die by themselves soon or later. So, take it easy about them and do not use any chemicals! It's not good to you and your environment. (05/21/2008)

By by mind fresh

Gnats on Houseplants

I tried the tip with the apple cider vinegar and the dishwashing soap. I also added a squirt of honey. I put this in a custard bowl in my house plant yesterday. After 24 hours I have about 30 gnats floating in it. My cat hasn't bothered the bowl. I think the vinegar drives her away. (06/03/2008)

By hpeter

Gnats on Houseplants

I had a problem this year and tried a couple of mothballs sitting on a paper towel in the pot. Left it there for a couple of days and voila' NO Gnats. (06/10/2008)

By Lynn

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October 25, 20070 found this helpful

How do I get rid of house plant gnats?

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August 21, 20070 found this helpful

How can I get rid of gnats! I have a lot of indoor plants and all of a sudden I am plagued by gnats. Have tried a mixture of cornmeal and water but can't get rid of them completely.

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