The title speaks for itself, but… We're growing several vegetables inside the apartment right now as it's a little chilly out right now (Arizona), and have a huge soil gnat infestation in every pot, I've used so many sticky traps, and have tried to stop watering so much but in the early stages of vegetable growth, they need water… I'm new to growing vegetables, as I only have mainly cacti and succulents… But how do I get rid of the gnats in the soil without making the vegetables inedible? (The plants get as much sun as the picture shows, depending on the day and whether it's overcast or not)
by TheLadyNightingale
16 Comments
Bonide, Captain Jack’s Dead Bug Brew as a spray and a soil drench. Organic, made from Rum remains when distilling. I have found it to be excellent in bug control. DO NOT USE ON FLOWERING OUTSIDE PLANTS!!! IT KILLS BEES, WE NEED BEES!! Just thought I would add this my lack of honeybees this year was beyond scary.
Here’s a [link to the method I use](https://www.reddit.com/r/plantclinic/comments/1gulu5k/comment/lxuypl7/), which has been pretty successful and does not require drying out.
Gnatrol can be a bit hard to find now for some reason, but if you search Ebay for “BTI Powder” it usually turns up. [Example](https://www.ebay.com/itm/356281487840?_skw=bti+8+oz&itmmeta=01JDWE7R42DCYH0RSVEB43716K&itmprp=enc%3AAQAJAAAAwHoV3kP08IDx%2BKZ9MfhVJKmyXla5IQMdXswlF2rChfr67M9%2BOupxCU9NTa1TyqQbAcDK4uqi9VqeIF9BKzdVRtZzKtcUydA3PqNd%2FN%2BHc6JKaWHTyb0IjWAmtM%2BxC%2Fqco4oXc7jjZYX%2FJrempm%2B9TpH70dAIwYL%2FyyzhI3NSUMVZbBGwFLQeHBQ4ddwv6HRJ0N1mm7iwFsuLXmNoZXbhVWZrxYXw6j2ue2gOpYxcgDVtz2PI0hk34OTTIaUcBQ7ceg%3D%3D%7Ctkp%3ABlBMUJSCn47vZA).
Next time I get a bad infestation, I’m going to try out the nematodes and see how they do.
Also: window light won’t be enough to grow fruiting veggie starts like peppers or tomatoes. Even if it’s south-facing and relatively unobstructed, you’ll get much better results with some overhead lights on them because the seedlings will grow straighter. A small fan to create some airflow will help the seedlings grow stronger stems and dry out the top layer of soil faster, making it less hospitable for gnats.
Only effective method I’ve ever found was nematodes
Hover them up morning and and night (and mid day if you are home). Disturb pots to get them moving so you can see them then diligently hover all you can get. Gradually they will reduce to nothing. Ive used this method a couple of times and have fully eradicated them, but takes time and you need to keep on it.
you can try mosquito bits soil drench, works great and is non toxic and safe
Get horticultural sand and put it over the top soil, only bottom water.
I use neem oil, you just spray the dirt/leaves when you water it and they’ll eventually all die off if you’re consistent with it. I also recommend scrambling up the first inch or so of dirt and spraying before you water.
Nemaknight nematodes in the shaker package. Sprinkle on soil every time you water until you stop seeing the adults on your yellow sticky traps. Works 100% of the time.
Use mosquito dunk water and bottom water your containers. The eggs are typically in the top inches of soil so if the top layer is dried out from bottom watering, the eggs will die off eventually. You’ll need to kill off the entire life cycle of the fungus gnats before you see them gone, this typically takes about a month.
I’ve only ever had success in getting rid of them by changing soil/medium types completely
Nematodes worked for us.
Can’t help suggesting letting it get down below 60 degrees for a few nights many of the species will die at that temperature
I overcame a severe fungus gnat infestation by repeated incantation of magical spells, and conjuring beneficial spirits of the netherworlds.
If it wasn’t that, then it was Mosquito Bits sprinkled on the top of the soil. The bacillus bacteria that mosquito bits are made of kills the larvae, interrupting their life cycle.
The adults will die off after a week. After a few weeks of normal watering there should be a significant reduction of gnats. I would imagine that it takes some time for the bacteria to reach all the crevices of soil medium to dispatch all the critters.
This after trying: nematodes, yellow sticky traps, soapy water bowls, sand, river rocks, rubbing alcohol, hydrogen peroxide, diatomatoish earth; as well as bonide, arber, and another brand insecticides (I didn’t try systemic insecticides).
I water all my herbs and food plants with mosquito dunks tea and have a VEVO light trap. Works for me!
I used diluted hydrogen peroxide and it worked well.
My experience with fungus gnats has mirrored the more credible or authoritative sources that properly addressed all of the lifecycle considerations: yellow sticky paper for the adults and gnatrol for the larvae. I don’t believe mosquito dunks are of sufficient strength to adequately kill larvae. In fact my recollection is that no matter what you try it takes a high dose. They walked with impunity in Diatomaceous-earth. They also live in my planters with just pon substrate. Maybe this is just a demon gnat over here ha