Getting rid of flies coming from potted plants?

Reply

  #1  
Old 09-05-17, 08:01 AM
C
Member
Thread Starter
Join Date: Jul 2010
Location: USA
Posts: 947
Received 0 Votes on 0 Posts
Getting rid of flies coming from potted plants?

I have two pots of house plants that somehow a certain type of small flies are coming from the dirt in the pot. How do I get rid of these flies? I hope it does not require replacing the dirt.
 
Sponsored Links
  #2  
Old 09-05-17, 08:40 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 23,730
Received 625 Votes on 578 Posts
They are annoying little gnats but not harmful. They live in the moist soil. Watering less frequently and letting the soil dry before watering is the best defense.
 
  #3  
Old 09-05-17, 09:19 AM
C
Member
Thread Starter
Join Date: Jul 2010
Location: USA
Posts: 947
Received 0 Votes on 0 Posts
So, just curious. How do the soils have these gnats to begin with?
 
  #4  
Old 09-10-17, 11:09 PM
D
Member
Join Date: Mar 2010
Location: Canada
Posts: 20
Received 0 Votes on 0 Posts
Originally Posted by Charlie2 View Post
So, just curious. How do the soils have these gnats to begin with?
.
Soil gnats can be present in almost any soil, even potting mix that you buy from a garden centre. In fact, unsterilized commercial potting soil is one of the most common vectors for many plant diseases and infestations. Another way is using gnat-contaminated soil from your own garden to pot a new plant. Yet another way is to bring a gnat-infested plant into your house; the gnats come along for the ride and lay eggs in the soil of your other house plants. And finally, they can actually just fly into your house and burrow into the soil of your house plants.

Pilot Dane mentioned the most obvious way to control them: Don't overwater your plants. Gnat eggs must stay moist to hatch. Therefore, an easy way to kill them is to turn the soil with a trowel every day, exposing the top 2" to fresh air, causing the eggs and larvae to dry out. The eggs hatch on a one-week cycle, so you may have keep turning the soil for a couple of weeks to make sure that you get them all.

Once you think the gnats are dead, you should start to bottom-water your plants. Since gnats and their eggs live in the top 2" of the soil, watering from the bottom ensures the top part of the soil remains dry. So, fill your sink with enough water to reach halfway up your planter, and let it sit for at least 15 min. or until you can feel moisture at the 2" mark (by sticking your finger into the dirt 2" down and feeling for moisture). This watering method will also promote a deeper root system which will strengthen your plant.

Another way to kill them is with insecticidal soap. To make your own, mix one cup of vegetable oil with a tablespoon of dishwashing liquid. Put two teaspoons of that mixture into a cup of warm water and stir. Then, pour enough of the mixture onto the soil surface to saturate the top 2". Putting the insecticidal soap in a spray bottle and spritzing the leaves will also protect your plant against certain diseases such as leaf fungus and mold.

Of course, those methods can be tedious if you have a lot of plants. So, there's a much easier way to get rid of soil gnats. Remove the top inch of soil from the planter and replace it with an inch of sand. The gnats don't like sand because it doesn't hold moisture as well and it's harder to dig through. Any larvae that are already in the soil should either dry out or suffocate. It's not as effective as the methods that I mentioned above, but definitely requires the least effort.

Good luck and good gardening!

[Sorry about the wordiness of my reply. I've had to deal with pests in my own garden and house plants, so I know a fair bit about getting rid of them. ]
 
  #5  
Old 09-10-17, 11:45 PM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 21,119
Received 3 Votes on 3 Posts
If they are really bad, you can probably find Gnatrol locally or on the 'Net. Works like a champ at killing any larvae and controlling them in the future.

When I was having problems after moving to a new home, I started baking all the potting soil I had before use and then kept it in sealed containers.
 
  #6  
Old 09-21-17, 07:51 AM
C
Member
Thread Starter
Join Date: Jul 2010
Location: USA
Posts: 947
Received 0 Votes on 0 Posts
Another way to kill them is with insecticidal soap. To make your own, mix one cup of vegetable oil with a tablespoon of dishwashing liquid. Put two teaspoons of that mixture into a cup of warm water and stir. Then, pour enough of the mixture onto the soil surface to saturate the top 2". Putting the insecticidal soap in a spray bottle and spritzing the leaves will also protect your plant against certain diseases such as leaf fungus and mold.

Of course, those methods can be tedious if you have a lot of plants. So, there's a much easier way to get rid of soil gnats. Remove the top inch of soil from the planter and replace it with an inch of sand. The gnats don't like sand because it doesn't hold moisture as well and it's harder to dig through. Any larvae that are already in the soil should either dry out or suffocate. It's not as effective as the methods that I mentioned above, but definitely requires the least effort.
This is awesome, thank you! I will give these suggestions a try.
 
  #7  
Old 09-21-17, 07:54 AM
C
Member
Thread Starter
Join Date: Jul 2010
Location: USA
Posts: 947
Received 0 Votes on 0 Posts
If they are really bad, you can probably find Gnatrol locally or on the 'Net. Works like a champ at killing any larvae and controlling them in the future.
Thanks! Is this the one, Gnatrol WDG, you use?
 
  #8  
Old 09-21-17, 01:48 PM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 21,119
Received 3 Votes on 3 Posts
Yep, but what I used was the older liquid style. This looks like a good change as it has a longer shelf life.
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: