Fighting them now lol from miracle-grow found a drop of dish soap in a spray bottle of water seem to keep them down.

Thanks, Bill. I would like to avoid that if possible! Still looking for suggestions for gnat-free potting soil.

Gnats are more of a symptom of an overly wet medium and an annoyance than a pox on your plants, though in some stages they can damage roots. Generally, using a less water-retentive soil resolves the gnat issue - I haven't seen a gnat in years.

Do avoid using dish soap on your plants, especially as a soil drench. It's harmful to the roots' lipid membranes, even at very low solution strengths. You can use mosquito dunks; or, a tsp of a 1.47% imidacloprid soil drench in a qt/liter of water will knock them right out straight off.

Al

I have been using MG Potting Mix (yellow bag) and MG Seed Starting Potting Mix (blue bag) for several years. I have not had any fungus gnats.

last year I had that problem and I came across an article to put your dirt In the oven for 1 hour at 350 degrees I did that this year and it seems to be working, I lost 90% of all my plants last year so I'm starting all over.

Hi, Cheryl. It wasn't the gnats that got your plants, it was the conditions that provided such a comfy home for them that caused the problems. Those conditions would be caused by over-watering, a soil that holds too much water at container capacity (container capacity is a measure of how much water a soil holds after the soil has been fully saturated and has just stopped draining), or both. Heat sterilization will kill living organisms, but doesn't cure what's sure to attract them all over again - like bailing out a leaky boat and saying the threat of sinking is gone, even though the hole didn't get plugged.

Al

You learn something new every day ,Thank-You

As I mentioned, when I had this problem before (years ago), I used a product called Gnatrol. It worked effectively, but it does require several treatments before the gnats are gone. And they have never returned, even after planting more houseplants.

Since I water my plants the same way all the time, I suspect some problems originate in the potting soil itself. If I overwater and bring on a gnat problem, shame on me. But, if I purchase potting soil that is already infected, shame on... (fill in the blank).

Just a heads up that Gnatrol uses BTi, essentially the same as Mosquito Dunks / BTK / etc. =)

Thank-You

I had terrible gnat problem last spring on all my new seedlings and pot plants. Switched to a dryer mix ( 5:1:1 ) and haven't seen a gnat since.

Yes - mirrors my experience exactly.

Al

I'm having a terrible fungus gnat problem this year. I use Jiffy mix to start most of my seedlings, but I do have a few plants in the bunch in MG potting mix this year. This morning I lost a zinnia seedling to damping off, which is the first time I've experienced it in 4 years of starting seeds early indoors. I don't know if the MG is the culprit, as I am guilty of over watering on occasion. I just treated my seedlings with a 1:4 hydrogen peroxide to water solution to hopefully kill the larvae and will now give them all a few days to dry out a bit. I'm keeping my fingers crossed that this will be enough to keep the gnats and fungus issues under control for the next month or so when I can start hardening off and planting out.

Try tipping your flats/pots at a 45* angle after you water (see fig. B vs fig. A - the shaded area = excess water)

and maybe get a fan on the seedlings to help dry the soil faster and strengthen the seedlings. Only water as needed. If done correctly, wicks can be a big help, too (see fig. E)

Undoubtedly, you'd be better served if you found some pine bark of appropriate size and made your own mix.

The gnat issue would almost certainly go away & the seedlings would love the superior aeration and reduction in the volume of excess water the medium holds.

Al

Thanks, Al. I did switch the fan on them and hopefully that will help. I have been meaning to try your gritty mix or 5:1:1 for the longest given the universally good reviews they have here, but haven't yet purely out of laziness. Perhaps this will be the year.

You made me smile. I don't want to call attention to your 'laziness' comment, but I do want to admire your honesty. Over the years, I've run into a LOT of people who would go to great lengths to pooh pooh the soils and think of a million reasons why they wouldn't use it, when the underlying reason is, they simply didn't want to make the extra effort required to put a soil together and then water more often. I think that's a perfectly valid reason to reject using it, and don't mind a bit if that's their choice, so why sacrifice their honesty on that altar?

There was one person whose husband made a big batch of gritty mix for her in the spring. She sang it's praises all summer long (on a different forum), but when it came time for her husband to make her second batch, he refused ..... and in a calamitous fit of sour grapes, the gritty mix went from being the best thing since cheese on pizza to the scourge of the earth.

Getting back to the topic ...... don't let the fact that you might not make the soil stop you from understanding the concept behind it. The concept is much more valuable than the recipes, and understanding it offers a lot of insight into how you can minimize the effects of excess water in overly water-retentive soils.

You've seen this? (click link)

Good luck w/the seedlings, and hava good wknd!

Al

I've been so frustrated with fungus gnats that I ordered 2 bags of Gnat Nix for all my container berry plants/bushes. I have 12 different varieties that all had them. Yesterday I applied a 1 inch layer on all of them so hopefully that will do the trick.

Nick did it work? I have a serious gnat problem with my container chilies, and I mixed the soil myself with orchid bark, perlite and a little soil, so I don't understand why because it drains well.

I tried a neem drench, but they're e back. I understand that we've had a lot of rain lately, but still. I'm afraid it's going to spread to my Meyers that are also on the deck, so I'm really curious if the gnat nix worked.

Atheen, If you mean soil, as in soil out of the garden, that might be the reason. Garden soil is very fine, and will run through the cracks of the larger particles and settle at the bottom. Through adhesive and cohesive action of the water and very fine particles, can cause perched water, and prime conditions for fungus gnat larva to thrive. You may not see them at the surface, but they could be living deeper in your container. You should try to maintain the same size particulate matter in all your ingredients. That garden soil, no matter how good and rich it may be, should not be there. If you add it for the nutrient value, omit it and make it up through fertilization when watering.

No, my apologies, i meant a little basic potting mix. Not soil from the garden. And they're was really not much if it, mostly orchid bark and perlite. That's what I don't get.

I read about trying yeast ,and it worked better than the apple cider. To each s own,GOOD LUCK:)

I rarely see fungus gnats anymore ... but then, carnivorous plants make up a portion of my indoor "jungle" and have wiped out most of the gnat population. Alas! Now my carnivorous plants have to go without their "snacks" during the winter. ;-)

But for those of you who don't have such flora, as has been said, mosquito dunks work well. Simply break off a chunk of the "donut" and put it in a jug of water to soak overnight. Next day, you can agitate the jug a little the water your plants with that water. Leave the dunk chunk in the jug as you will be able to reuse it. It isn't an instant kill but will do a number on the gnat population as it kills off the larvae. Meanwhile you can set yourself on the long term approach of rounding up the ingredients for the 5-1-1 mix you've heard spoken about.

Great : )

We bought Miracle Grow nat control and its loaded with them.

Wait the gnat control is loaded with gnats??

Is this a soil?

Same for me as GG stated above. Organic components added to bagged soil mixes is food for fungus gnats and problem becomes much more apparent indoors during winter. And the situation is not helped by the fact that bagged mixes tend to hold more water longer.

Agree - Fungus gnats love any organic component that breaks down quickly. Especially high on the list of materials that send gnats into an orgiastic frenzy are the various meals, especially blood, but also alfalfa, cottonseed, hoof, horn, feather meals, which are used in organic slow release fertilizers as the primary N source. Fish and seaweed emulsion is like dessert. Rounding of the conspicuous list would be worm castings, unfinished compost, mushroom compost, and manure.

Al

We should note that spontaneous generation (life from nothing) has been disproved. :-) If you don't have fungus gnats, you won't GET them from using these slow release fertilizers. Case in point, I use them indoors and don't get them. Unless there are FG eggs on my Milorganite (pretty much zero probability), I won't.

ETA: I still don't recommend using these in indoor pots much more than as 10% to 20% of your feeding for most people. Other factors do come into play (percentages which some critics are quite careful to ignore, I might add). Use synthetics for the rest of your feeding under most circumstances.
/ETA

And if you do, the cure is easy: most plants can be watered with 1 part hydrogen peroxide to 5 parts water, and also either put up sticky fly paper to get the adults or put out a small glass of apple vinegar (either work fine).

Or use BT mosquito dips, break them into bits and scatter on the plant surface. Water in. And then use the fly paper or apple vinegar.

End of problem.

Most plants aren't harmed by FGs. Poinsettia being the odd exception, and even there, only in severe cases.

Absolutely true as I found eggs throughout the soil when I opened it. I won’t buy it again

Dan Are you sure you saw gnat eggs? They are very small and need at least a hand lens to see them. Or may be you have very good eyesight. May be large clusters are more visible. I have not see one myself but then I do use MG soil either.

Yes for sure and I pinched most of the eggs to destroy them. I’m very familiar with these eggs and gnats. the last sealed bag of soil was opened today and loaded with the small yellow eggs.

I can't believe this thread that I started five years ago is still going... and that Miracle Gro still has not figured out a way to deal with their fungus gnat problem. By this time, they must be tired of replying to customers' complaints about it!

If the "eggs" were large enough to be seen easily, they weren't eggs. More likely they were the timerelease fertilizer pellets.

Fungus gnat eggs are translucent and around 200 microns long, which are extremely tiny to the naked eye. With 40x loupe magnification you should be able to get a decent look. If they are big, round, and bright yellow that might be fruiting bodies of a fungus.

I also got fungus gnats in two different houses from MG Moisture Control potting soil. So annoying. The way I got rid of them was to hang fly strips in the windows where they hung out. Nothing else worked. I did get rid of them this way. I will never buy this soil again. Just terrible. Does anyone have a brand they like? I'm sick of this whole experience.

Im a 100% convert to using sea soil. (also afd perlite and worm castings). it uses nutrients and minerals from the sea. ever since i switched over all of my plants to this soil mixture my plants are thriving and zero bugs in over 2 years!

What the heck is 'sea soil'? Never heard of it.

It's more important that what nutrients are available are only those the plant needs for normal growth and available in a favorable ratio, than where the nutrients came from; plants cannot absorb anything in organic form. Also, a container medium's structure is it's most important asset, the second is how long it can retain that structure while in use. A medium's ability to provide nutrition for the plant should be very low on the list of things to focus on, this because it is monkey easy for the grower to institute and take absolute control over their plants' nutritional needs; and, there is nothing in worm castings a plant needs that it can't get from a good soluble synthetic fertilizer. Worm castings diminish a medium's singular most important asset - its structure.

Al

Looked it up. Looks like everything you described is exactly why that sea soil is rendered useless in containers. Thanks

Miracle grow moisture control caused a serious fungus gnat problem in my garden. l have been gardening in containers for years and never a problem before using this stuff!