I ordered Miracle-Gro soil about two months ago (NEVER AGAIN) to repot one of my plants, and now—BAM—gnats everywhere. I’ve tried everything, and nothing is working. Attaching screenshots of the products I’ve already used.
Here’s what I’ve done so far:
1. Cinnamon dusting on all my plants + Captain Jack’s Neem Oil Spray → No luck.
2. 1:4 hydrogen peroxide soak → Didn’t help.
3. Sticky traps (replacing weekly) → They fill up like crazy, but the gnats keep coming.
4. Mosquito dunks (BTI treatment):
• Soaked 1 dunk in 1 gallon of cool water for 2 days, then watered.
• Reused the same dunk, let it sit for 2 weeks, then watered again.
• Checked the traps, and they’re FULL—more than ever!
5. Just ordered live nematodes (brand attached). Does anyone know how to use these properly?
What do I do now?!
– If I repot, how do I keep this from happening again? I’ve heard microwaving soil ? Using sand on top of soil?
– Is there anything else that will actually work?
I am losing my mind over this—please help before I throw my plants (or myself) out the window. I have read nearly every post on this Reddit related to Gnats, but please let me know if I am missing anything.
by Chotuchigg
13 Comments
Your soil is crazy dense. Fix that. Should help with the gnats. Also when I get the on occasion I spray the soil and them with rubbing alcohol
https://preview.redd.it/vbdkuuygowle1.jpeg?width=702&format=pjpg&auto=webp&s=f142d192dd1a7f8c3db4945979e738d4c659b9e6
This will help. And bottom water your plants
Get horticultural sand. Put a layer about 3/4 of an inch thick over the top soil. And only bottom water when the roots are dry.
Change your soil to a better draining soil and start bottom watering! As for dealing with current infestation I’m not sure
Use more porous soil, water from the bottom or cover the top. Have you considered getting a plant that eats gnats? Pinguicula do
Azomax
I watered with a hydrogen peroxide mix and also let the plant dry out fully. I’ve also seen people bring plants home from box stores and wash them entirely roots incl and put them in new soil, never tried it myself, but I wish you the best of luck! fungus gnats are my mortal enemy
edit to add, you could also try a layer of diatomaceous earth on top of your soil! it will kill them by giving them a ton of tiny cuts and they dehydrate and die. make sure to only bottom water your plants too.
I also used a hydrogen peroxide (1 c peroxide to 4 c water) drench as a last resort, then mosquito bits. It does kill any beneficial guys as well as the gnat larvae, tho.
Keep up with the BTI. I had a bad outbreak (which also came from miracle gro potting soil). It takes a few months to really wipe them out and keep using the sticky traps until they are under control.
I keep a 5 gal jug w/ spigot full of mosquito dunks to fill my watering can from.
Stop all watering for a few weeks. Looks like you’ve got a Sago and maybe a ponytail and they’re both hearty enough to deal with no water for a while. I have a few hundred plants and every time I start to see fungus gnats my first move it to stop watering everything right away except for the most thirsty plants. When I start to water again they get a mixture with mosquito bits for a few weeks and that does the trick. But you have to let them dry out to help interrupt the life cycle. That soil is way too wet to create a hostile environment for the little buggers.
Add a pingulata
I’ve had really really good results with Bonide Systemic Houseplant Insect Control. They are granules you sprinkle onto the soil and water in and it kills the gnats and their eggs. I had thousands of them Infest my all of plants one summer and this is the only thing that killed them for good. Mosquito dunk tea is good too but I swear by bonide.
You have a ton of other suggestions on here but I was just reading about putting coffee grounds on top of the soil. If your a coffee drinker then that would be something you already have on hand.
My brother works at a greenhouse and bright home some tulips for me. I started noticing little flies everywhere. Looked up and googled it what they were and am hoping they didn’t imayge my other plants. Lol luckily most of mine are succulents so don’t have to worry about most soil