PERLITE vs VERMICULITE (Water/Air/Fungus Gnats)

[Ardek]

Curious on input from the community on what you'd suggest Perlite or Vermiculite mixed in with my soil for an indoor grow.

I understand they both aid in soil water retention and aeration, but not sure how that affects marijuana specific indoor grows.

Vermiculite - Aluminum-iron-magnesium silicate, holds a neutral PH of 7.0, and can hold 3-4 times its weight in water. It also holds magnesium, potassium, calcium, and phosphorus. Holds more water than Perlite because of its porous springlike pores.

Perlite - amorphous (silicon rich) volcanic rock (glass like), holds a neutral PH of 6.6 - 7.5, and holds more air (not as much water retention).

Personally, I'm planning to use Happy Frog potting soil mix, but besides peat, and some bark a couple other things, I don't see that is has much of either perlite or vermiculite.

I'm also specifically looking to see which is best to ward off fungus gnats; I would think the perlite (as like a layer at the bottom of my pots).

[Mr.furley]

My vote is for perlite.
I do not want water retention but more drainage, water retention will cause slower growth and can lead to overwatering and root rot, cannabis roots like o2.
A 1 inch layer if perlite on top of your pots is a common practice to fight/ward off gnats.

[az2000]

I understand they both aid in soil water retention and aeration, but not sure how that affects marijuana specific indoor grows.

My understanding is: Perlite is known for drainage, faster drying. Vermiculite is good for water retention.

For example, Pro-Mix HP has ~35% pelite. It's known for being fast-drying, low-moisture holding. Pro-Mix BX has less perlite, and includes vermiculite. It's known for remaining wet longer (often use instead of HP when growing under HPS whose radiant heat can dry HP to fast.).

[Gingerbeard]

My two options for fungus gnats are to mix diatomaceous earth in with your soil and/or make sure you have good circulation over the top and bottom of your soil. Fungus gnats can find their way into your pots through drainage holes. Keep the bottoms of your pots raised a half inch, or so, off the floor and provide circulation there as well. I haven't had a single one in my houseplants since I started doing the DE.

[az2000]

Bonide and EcoSmart (other brand names) have a pungent spray with rosemary oil, thyme, clove oil. All I have to do is spritz that a couple times on the soil surface, and around the saucer. That keeps them in check. (I see them drop out of the air 8" away. It's really pungent like that.).

I also cut out white posterboard to lay over the container (cutting a slot from the edge to the center, for the stem to slip through. I lay two on top of each other to block the cutout.). That impedes their access to the soil, and retains the pungent smell from the spray too. (It also reflects light back into the canopy, which is nice. But, in a humid climate it could cause mold. In which case, use panty hose.).

I don't try to stay gnat-free. I don't treat them like thrips or mites. I just try to keep them down. I find the spray and covering the container does that. I don't bomb them just because I see a couple. It's not a big deal if you don't let them takeover (unlike thrips or mites).

Something else I recently disocovered. Fill a small glass with apple-cider vinegar diluted 50% with water. Put plastic wrap over the top (seal it with a rubber band around the glass). Poke 2-3 holes in the top. The gnats will enter,drown.

What's interesting about that: I can't get that to do *anything* if I put it in the tent. If the flys are around the plants, they don't care about the vinegar. But, if I put it in the kitchen, eventually the flies will go elsewhere and *straight* to this trap. It's the strangest thing. I can put one of those in the tent and catch *nothing*. But, if I put it on the kitchen counter, I'll get them.

(Diatomaceous earth never worked for me. It seemed to wash into the soil. I use a light, airy soil. So, maybe my soil doesn't hold it well. I've read DE may be useful as a soil amendment, to supply micronutrients. I'm sure it's not bad to add. But, I never noticed the gnat population affected.).

[Gingerbeard]

az2000 I mix the DE in with regular soil. Sounds more dense than your mix. I only had a problem using the DE when I was sprinkling it on the surface. Didn't do a bit of good when I did.
My thought on the gnats ignoring your tent treatment is they have something better to go for in your soil?

[Gingerbeard]

Come to think of it, I made the same recommendation about doing the ACV bit on some work plants. Took care of business. Like you and DE, I've never otherwise had luck with ACV.

[Ardek]

Hnmm... My gnats never left the grow tent. I mean Id definitely see some come out when I went down to water, and I have indoor house plants upstairs, but they never came up and infected my other plants or my drains or anything.. Just liked my weed.

Thankfully I was using organic soil, so they had plenty to feed on in the soil and didn't hurt my plant roots at all.. I also managed them using a 4-1 peroxide/water mix (but that only kills the larva, doesnt touch the eggs or adults, and a single adult female gnatt can lay over 200 eggs in the week its alive).

But I'll but super happy if I don't have to deal with them at all this crop. I'm almost positive they either came in from the clones I got or the organic soil from the supply store. I treated my soil this time in a 200+ degree F car over the hot days of the end of summer.. So I know if there were any eggs in there (like from sitting in the supply store) they are dead. best way to kill them beside baking your dirt in the oven, lol

[az2000]

Ardek, I leave my tent doors open during the day (that's a risk, because you can easily forget to close them when lights go out). All I know is, I rarely see a gnat in the tent now. But, I have 20 dead ones floating in the 50% dilute ACV in the kitchen.

I did see gnats in the tent a few times earlier. I spritzed the pungent rosemary, thyme, clove stuff (Bonide, Captain Jack's, EcoSmart makes it). But, that's when I had the idea to use the ACV (because it works in the kitchen when I have gnats). I put a small condiment bowl it in the tent (covered with plastic wrap 2-3 holes poked in the top). I only caught 1 gnat. They never went to it.

When I moved it to the kitchen, I stopped seeing gnats in the tent, and saw the body count rising in the kitchen.

I would definitely try it. It seems like the gnats are noseblind when it's near the soil. They think "oh, that lovely smell must be coming from the soil." But, if it's away from the soil, and they get remotely distant from the plant, they suddenly say "oh, what's that I'm smelling" and go straight to it (nothing nearby to confuse them).

[Ardek]

Thanks for the feedback though guys, I'm headed out now to grab some perlite and add it to my dirt and bottom of my pots.

*edit - So I know how much to put at the bottom of the pots, but how much should I mix in with my soil. Like 10%??

[Tersky]

So in reference to gnats, i have tried ACV with no luck. They seem to go after anything BUT the ACV though it might have been old. I do DE personally but came across this vid when i was starting my microgreen. This guy tried ACV and didnt have much luck but then tried Redd's Apple ale instead of ACV and said it worked much better. IDK never tried but thought i'd just share! https://www.youtube.com/watch?v=rWmF1VaBSDA

[az2000]

Did you try the ACV away from your grow area?

I didn't have any success until I moved the ACV away (30' or more). But, that may rely on leaving the tent open, for the gnats to explore. If they're locked in the tent all the time, my "move it away" idea won't do anything.

[Tersky]

Yeah i tried it in my kitchen by the dog food. I didnt cover the cup with cellophane with a hole though...that might also be the issue. It was crazy. i saw gnats by the food bowl, put the cup there and the damn gnats moved to another part of the kitchen! Moved it over to that spot, and they moved back to the food bowl. It was more of a repellent than an attractant. I think i ended up getting one gnat out of that lol.

[az2000]

The plastic wrap over the top (with 2-3 bb-sized holes) traps them. I believe a drop of dish soap would help them drown. Sometimes they get into the dilute ACV, climb out. If it's not covered, they climb out of the bowl. But, with the cover, very few get out.

Maybe I noticed this working because I'm growing in cactus mix right now, and it's not very soil'ish. Maybe the gnats aren't attracted to it like soil. But, I did see gnats at the plants, and put the ACV there. Only caught one in 2-3 weeks. Keeping it away from the plants, I've killed a lot. I had to empty it and fill it again with fresh ACV/water. I add a pinch of sugar to help it ferment. Maybe that helps too.

I'll definitely try the Redd's Apple Ale you mentioned. To me, anything that keeps their numbers down is good. I don't go nuts trying to erradicate them. I don't mind a seeing them occasionally. It's just when it's an infestation. So, anything that makes life harder for them is what I aim for.

EDIT: I noticed in the video he distinguishes between fruit flies and fungus gnats. I may have been getting baby fruit flies. I don't know the difference.

[SoOrbudgal]

My 2cents....I use vermiculite in my outdoor soil mix do to water retention. I use perlite in my indoor soil mix and also in my outdoor i'll recycle indoor containers soil in my summer grows. But I only use perlite indoor mix to be clear.

[Guest]

If you're in soil you will wanna use perlite, you want it to dry out asap for oxygen to get to roots... Esp indoors

[mactheman]

yep i reckon perlite is a must for inside growing in potting mixes ,,,its really helps with drainage etc,,,,,mac,,