well u gotta be careful about that, the stuff to kill fungus gnats is Bti (Bacillus thuringiensis subspecies israelensis) which targets larva of mosquito blackfly and fungus gnats only, caterpillar killer is Btk (Bacillus thuringiensis subspecies kurstaki) which will target leaf and needle eating caterpillars but not gnats.
1 Like
I disagree ! Not that itās ever happened to me but thereās growing mediums out there at nurseries, grow shops,or big box stores that have FG in them already before one even purchases it, so one might be fighting an uphill battle before the mix hits the pot! Iām sure others here can verify to this statement! Any others want to pipe in here?
3 Likes
I am using fox farms ocean forest organic soil I have read online that most soils contain FG I donāt think I am over watering the plants look fine and wen I do water I am only using a small amount I am not filling the pot I am going to give them a dry period of at least 7 days then with try watering from the bottom I have covered the top of soil with diatomaceous earth and before that I had Watered with BTI water
1 Like
Checked on plants this morning spotted wot looked like a tiny white or grey coloured fly crawling across top of soil caught it and killed it I had covered top of soil with diatomaceous earth and this little fucker didnāt seem to affected by it as it was just crawling about in it
3 Likes
The D.E. is a slow kill, it works by scraping up insects shells (exoskeleton) or āskinā then they lose their fuids and die. Itās not like spraying a product (bug spray-raid) be patient.
7 Likes
agree, I think āletting the soil dry outā is bad advice for gnats, they donāt seem to care if the soil gets dry or not, only Bti kills them in my garden. If you let the soil get dry enough to kill them your plants are dead.
FGās are a normal part of organic growing. I see them every single time. A few waterings with Gnatrol after transplanting eliminates them or reduces them to insignificant numbers. Nemotodes work too but you need to apply them every time you transplant or mix soil which is expensive.
2 Likes
Ya youāre right, I guess just telling people to dry their pots out is bad advice.
For me tho, pots that ALWAYS stay wet on the surface and grow algae as a result, are breeding-factories for fungus gnats. So I let the top few inches (of a 2 gal.) dry out every few days. (I also use BT and nematodes weekly tho)
The greenhouse I work at is a different story tho. Algae and gnats on almost everything because they water too much. Then they spray poison for gnats lol.
1 easy gnat inhibitor is: Cover the tops of your pots with something. Lids, or 2" of hydroton pelletsā¦
3 Likes
the problem is ādrying outā can mean anything. I also wait to water until the top surface of the soil is dry & crispy. But that doesnāt seem to stop the gnats at all. Theyāre still scurrying around & doing their gnat bullshit! 
if you wait till the top soil surface is totally dry and dust with D-earth it works great, you can see the little bastards flailing around & trying to escape and dying, they absolutely hate the D-earth. But then I need to water the next day and the d-earth stops working.
3 Likes
Iāv even went as far as putting a 1/2 inch layer of sand on top of the surface which I believe helps deter them I donāt think they can dig very well!
4 Likes
Almost every time I use any soiless mix like promix or sunshine mix it always contains fn, or white flys, something. So, I would disagree, if it were hydro like rockwool or clay pebbles, and you have fg, yea, your fault.
1 Like
Sunshine mix is on my never again list, I have bought exactly one bag that was supposed to be organic and no nutes added. My plants began to develop nute burn and I discovered those little time release pills all through it.
3 Likes
I just bought a few bales of this, my new organic base mix, supposedly pro-mix is very ācoolā:
http://www.pthorticulture.com/en/products/pro-mix-mp-mycorrhizae-organik/
theyāve been sitting outside this summer at the store, Iām sure theyāll have some gnats.
2 Likes
Are you talking about mosquito dunks or bits? I got lostā¦
heās talking starter āchargeā of fertilizer in the soil mix. Itās usually chicken āguanoā in the organic mixes.
1 Like
Actually Iām speaking of neither of those, these pills are maybe 1 or 2 mm in diameter there is one type that goes by the name of osmocote. They are dry usually inorganic chemical fertilizer with a dissolvable time release coating you will find them in all potting mixes that say feeds for"X" months
1 Like
A picture of a few of the actual pills or balls I am speaking of
2 Likes
theyāre definitely not supposed to be in organic soil! Yuck. I notice that all the potted plants I buy from nurseries come with Osmocote pellets, seems like the industry standard.
1 Like
imagine if the potting mixes came filled with cannabis seeds instead! Thatās a business opportunity for a soil company ā¦