SueVT said:I am also considering baking the seedling mix before use, to eliminate soil-borne gnats. Seems like a lot of bother, but the gnats last year were insane!

Last year i baked all soil EXCEPT the miracle grow seed mix i added at the last minute when I was in a rush... (purchased from Home Depot or Lowes... cant recall). The gnats stuck quickly... I'm pretty sure the commercial miracle grow was carrying eggs... which was quite a disappointment. So baking at 200 degrees for 30 mins is a good idea if you are not planting all that many seedlings... if you have tons of seedlings it can be a bit impractical... i'm staring at 2+ cubic yards of soil that I intend to use... I just do not have the will to back that much.... so I am going to water with Gnatrol every so often

Gnatrol took care of my problem quickly and effectively. Even if you started out with eggs or gnats, gnatrol will resolve it. Give Gnatrol a try first before attempting any expensive solutions is my advice.

Sue, how easy and quick this fix would be. Simply sit back and let the soil dry out, and no more fungus gnats! If that were true, there would not be a major pest problem going on with fungus gnats, but there is.

I've researched this topic for years. Tried the advice I read, sometimes more than once, thinking I hadn't done it right. Now I'm tired of the yada yada yada! Beginning with the number one yada - moist soil.

If you could see how dry my skin is right now, and my fly-away hair! The furnace barely shuts off and my whole house is dry. Including my hundreds of daylily seedlings.

I've grown plants in pots for over 40 years. Tropicals and vegetables. Inside under lights and outide during the summer. I know that the number one killer of house plants is over watering.

For every person, web site, and institution that tells you what works for management of this problem, there will be one that says it didn't work for them. They didn't work for me. So I no longer want to hear about moist soil, Hydrogen Peroxide, Cinnamon, Cedar Oil, sand, Diatomaceous Earth -

https://www.mdpi.com/2075-4450...
It has been hypothesized that physical barriers such as sand or diatomaceous earth placed on the surface of the growing medium would negatively impact fungus gnat adults when they emerge and/or prevent females from laying eggs [42]...However, it has been shown that placing diatomaceous earth or sand on the growing medium surface did not have any effect on fungus gnat adult emergence or inhibit females from laying eggs because these physical barriers contain small openings that allow larvae to pupate, and adult females to lay eggs [41,45].

pieces of flea collars on the soil, and Neem Oil. Thank you very much.

Tracey, I've already got 5 dead seedlings! I'm not waiting another month! After I put the seedlings back in the bag with the pest strip for another 24 hours, I will use Sevin Dust if I still have a problem!

I'm sure many of you will disagree, but I soil drench all potted plants with Sevin 24 hrs before I bring them in the house for the winter. I also lightly syringe and wipe all the vegetation with plain water just before they come in. This advice was from The University of Michigan Cooperative Extension. After battling them using all the home remedies and organic remedies I found this to be the fastest and most effective. 1/4 tsp Sevin to a quart of water. Water plants until the potting soil is thoroughly saturated and water runs out the bottom. The plants are then free of all soil pests and remain that way for the duration.

My infestation began with a potted gift amaryllis from White Flower farm 3 Christmas's ago. Inspite of following all the proper cultural practices, such as allowing the soil to dry throughly between waterings, the little buggers thrived and spread. I buried slices of potato in the soil to trap the soil larva. I used the yellow sticky traps for the flys. I tried the organics, which in my opinion are a complete waste of money and time. I could knock down the population levels but never eradicate them. Then, in utter desperation, I soil drenched with Sevin. I've not had a fungus gnat since."

I also want to say that my babies are looking so clean and healthy and will soon need their first haircut!

Mary, Just trying to help. I struggled with this problem in a big way for years. And I tried everything. I like to pass along seedling saving information that I find successful. I am not an easy sell. All I can say is things drastically changed for the better in days after application and I've used it ever since with no gnats anywhere.
Good luck!

Sorry, Tracey! Didn't mean to snap at you!

No problem. Just wanted you to see my perspective on this where I was and where I am. It's just so so nice not to see those little buggers flying around. Gnatrol was a miracle here!

Tracey, I so agree. It's nice to have thing that work to help you. I believe that between the BT, yellow sticky traps, and this pest strip, I might get there as well!

Hey Mary, Sevin is probably the least toxic chemical in our arsenal: http://pmep.cce.cornell.edu/pr... with an LD50 number almost 400. This does not mean we should be cavalier in it's use, but a quick drench, carefully done, is invaluable in solving this particular problem. Use gloves, and clean up after.

Great questions and even greater answers, thanks so much to everyone for their participation. I hate fungus gnats!

Mary I agree, and you should have seen me desperately putting peroxide on everything. Pretty comical. I was stacking seedling cups in the shower stall and pouring it all over them. Made no difference.
The diatomaceous earth only worked on the adults, because it gets into their exoskeleton and ruins them. However they always bounced back. Meanwhile my bedroom looked like the surface of the moon.
I poured half a bottle of cinnamon on one of the seedling flats, which smelled good, at least the gnats thought so.

I am not starting the seedlings until February, in large part to avoid four months of gnat fighting. Fingers are crossed about the gnatrol!

Good discussion here.
Before I start my daylily seeds, I think I'll bake the seed starter mix, order some gnatrol, and remember the 1/4 tsp Sevin dust in a quart of water drench, just in case. I only lost a few seedlings last year, but I'm sure there's gnats aplenty lurking in my few house plants. Maybe I should pre-treat all them before I start, just to knock out the reservoir.
Mary, best of luck!!

Diana, that's a dang good plan!

I've also had great luck with Gnatrol, but it helps if you catch the infestation early, because it takes a while to work.

Bayer Tree And Shrub Insect Control Also works great, killing both adults and larvae, but is like using a cannon to kill mosquitos.

Imidacloprid is the systemic insecticide in Bayer T&S, and is why the product is so expensive. Imidacloprid is also detrimental to bees, so I only use Bayer T&S on small seedlings which aren't expected to bloom for another year.

I found a pretty cheap source for Imidacloprid in the form of granules intended to kill grubs in turf.

I also recommend Gnatrol or Knock Out Gnats at the first sign of infestation. But keep in mind that it has a shelf life so just order what you need for this season. You can find it at very low cost at Amazon in the smaller packages. Gnats LOVE laying their eggs in most potting mixes that contain sphagnum peat so avoid buying broken bags!! I made that mistake one year when I bought a bargain bale of Pro-mix that had a hole in it!

I guess if you wanted to go completely chemical free you could grow some carnivorous plants. Someone in last year's swap said she had butterworts (Pinguicula) for that purpose and was offering seeds last year. She got the seeds to sprout easily so that's an eco-friendly avenue you might explore.

Right now I have some small spiders living under my growlights that are doing the same for me. But I like spiders.

I was reading on a Facebook group... someone on there was talking about using a medium made out of coir and perlite. She didn't say the ratio... but stated zero gnat issues since switching 🤷🏻‍♀️ Anyone have experience using this??? I'd like to try it... I'd assume the ratio would be 2:1 ish?

Taking my car in this morning for oil change, tire rotation, etc. When I get back, I'm gonna do the treatment again, for any of the eggs that may have hatched. I was really surprised that there was no odor, and no change in the seedlings. Only 3 or 4 new gnats stuck on the sticky traps. The babies are so beautiful!

Thanks for the Gnatrol info. I'd never heard of this product, but I will be buying some this winter.

Driving home from the service station, car started making horrible noise and vibration. One of the tires was coming off!

Guy came out and fixed it so I could get back to the station. They gave me temporary lug nuts, three of them were lost off the loose tire! They are ordering a new set for all the tires, no charge to me, plus they gave me my money back they had charged me for the oil change, etc.

Got the seedlings set up for their treatment, and now I'm making a huge pan of chicken broth for soup! What a day!