You can get gnats at anytime of the year, but you may see them more in the spring and summer when you start potting a houseplant for the first time or repotting a houseplant that has outgrown its container. They are very very tiny black flying bugs. These gnats seem to come from nowhere and can be so aggravating. One gnat can produce 100’s of offspring in their short life of 28 days of life and 7 of those days is spent in adulthood. They can make your life miserable and destroy your plants. Totally eliminating them may be impossible, but getting them down to a few is possible.
Gnats lay their eggs in wet environments like wet soil and moist compost. The eggs produce larva that will feast on the fungus that grows on top of wet soil, algae and yes your houseplants and their roots. Gnats will gather around overwatered houseplants and many greenhouses. They love the hot temperatures found in greenhouses and in homes that are in the mid 70’s or a room used for a grow room, with temperatures that are around 77 degrees. Some greenhouse owners will up the temp to bake them and kill them.
There are many remedies out there that people use to try and to get rid of their gnat population. There are a few things I have done that have worked for me. It was basically a trial and error experiment to find what worked for me.
My firs mistake was my idea of going organic with my houseplants. I quickly realized that this was okay for outside plants, but not so good for the inside plants. Don’t get me wrong organic potting soil did great for the growth of my plants and they were thriving, but gnats really love organic rotting soil. Within 2 weeks of planting all my houseplants in this awesome organic potting soil the dreaded black, flying mosquito like, but smaller bugs arrived in full force. Not one, two, three, but an army of these pesky bugs. Fungus gnats live on the top of the soil about ¼ to ½ inches deep.
For the purpose of this article I will assume that many like me will not want to re-pot their plants again after going through all that the first time. I chose the latter. So if you are repotting or potting up new house plant and you don’t want to deal with those pesky gnats, it might be best not to start out with organic soil for your inside plants.
*Now, if you have had a gnat problem for a while and noticed your houseplants are dying it is a pretty good bet the larva is eating your roots. If your plants have reached this point I would strongly suggest changing your soil completely, rinsing your roots of all soil and repotting in regular potting soil. To check to see if you do have a gnat problem you can take a small wedge of a potato lay it down on the soil, in a few days check the underside of the potato. The gnat larva will be come to the top to feed.
Now, for those who like me, don’t want to redo what we had already done. Here are a few suggestions. They worked well for me and hope they will for you also.
First, I bought some sand (I bought the sandbox kind) from a local garden store. Don’t just go outside and get sand from outside because it can be infested itself with gnats and other insects you don’t want in your house or feeding on your plants. Place the sand about an inch thick on top of the soil of your pot. The reason for the sand it that gnats can not bury into the sand, thus not being able to lay their eggs in the soil of your plants and any in the soil can’t get out and will die.
Second, another thing I did along with the sand was to put cut a small plastic water bottle in half. I put apple cider vinegar in the bottom of the water bottle about ½ full in the bottom. I then put the top ½ of the bottle upside down into the bottom. The gnats will be attracted to the vinegar and will then be trapped in the bottle, when the vinegar is full of gnats, just empty and refill and start again. Keep doing this until you notice no more gnats. I also for an extra measure I put some yellow sticky tape on the bottle to attract the gnats. What the vinegar don’t get the sticky yellow tape will.
Killing and catching the adults is the easy part, getting Rid of the gnat larva is another matter and a little harder.
The larva flourish and love wet soil, so your first plan of action is to let your plant’s soil completely dry out. The larva can’t not thrive or develop in dry soil. Let your soil dry out for a while. Your plants will be fine; more houseplants are killed because they are over watered than underwater. Once your soil is almost completely dry now you can go to the next step.
You need to mix 1 part of pure hydrogen peroxide or H202 to 4 parts water. I mixed up a gallon. I filled the gallon jug up almost ¾ full of water and then the rest with the peroxide. It will take a lot of peroxide to kill your houseplants, so this amount will not harm them. Take this solution and water your plants has you normally do, making sure the top layer of the soil is water well. You will noticed the top of your soil will start to fizz this is just the reaction of the peroxide coming in contact with the soil. With this solution the gnats or most will die on contact. When the fizzing stops your plants benefit from the oxygen the peroxide produces along with the water.
If you follow all the procedures above you should be rid of your gnat problem in no time. I only had to repeat all the above procedures twice and had no more gnat problems. So this year I will start out using non organic soil and follow the above if need be.
*One important note, if you are bring your plants in for the winter you will most defiantly be bring in bugs and gnats into your home. Warmer temperatures of the home will invite your gnat population to produce and you will be fighting these bugs all winter. For plants being brought in for the winter, I strongly suggest you completely repot with fresh soil. Take plants out of pots; rinse all soil from roots and plant. Before bring you plant it, spray your plant with neem oil to kill any bugs or gnats that have attached themselves to your plant. Now that you have sprayed you plant, have new soil for fresh potting your plant is ready to come in for the winter.
Hope this information has helped and you are now gnat free and you and your plant are living in peace.