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Adding top layer of sand - some concerns...

CFP65

Member
i fighted both the Aphids and the gants too,
i tried everything but to no avail,
then i took the decision to clone everything and discard of all dirt in my grows
and start all over and that did it.
no more aphids/gnats
 

Brother Bear

Simple kynd of man
ICMag Donor
Veteran
I tried sand once back in 08, here is a pic of Blowfish with sand on top the soil.

58165100_2606.jpg


I hated using sand. Once the soil dries up it runs down the sides and out the holes. Gets everywhere, forms a hard crust and won't let water through.
Get a few fly stickies and start to water less, or better from the bottom, they will go away for the most part.
I have actually come to accept them as part of my grows, seems like they show up in every single bail of peat in the world :)
And if kept in check, they will do no harm to the grow, Gnats that is.
 
S

Smoke Buddy

I had fungus gnats for several cycles a while back. I tried many things like neem, DE and also mosquito dunks ground up and mixed into the top 2 inches of containers medium. Nothing that I tried got rid of them for long until I went with sand. I used clean sand from the local gravel co. I basically put 1 1/2 inches of moist sand on the top of the soil and smoothed it over. In a day or two it dried into a hard cement like barrier. It was fun watching the adult gnats pacing back and forth on the hard sand surface. The plants appeared to droop and looked shocked about 24 hours after I applied the sand but my bro insisted they would pop right out of it and sure enough they were fine the next day. I let them go about 4 days with no water which was a day longer that I had been watering. I then broke out a section of the hardened sand and watered into the holes it created, then covered them again... after about 2 weeks like that I took all of the sand out and have not seen a gnat since. Sand is a very effective method when done properly. Hope this helps.

:rasta:
 
Put sand on them last night, gnat population has dropped big time so far. The only thing I am worried about is the sand hardening and causing problems when watering. Think I'm going to do as another poster mentioned and make holes in the top of the soil when watering.

Thanks for everyones help and advice.

The Captain
 
I don't like the idea of sand just because it's keeping your soil from breathing..

I just used a solution of 1 part hydrogen peroxide 3% and 4 parts water. Will say if it works in a few days.
 
S

SeaMaiden

How does something as porous as sand keep soil from breathing?
Put sand on them last night, gnat population has dropped big time so far. The only thing I am worried about is the sand hardening and causing problems when watering. Think I'm going to do as another poster mentioned and make holes in the top of the soil when watering.

Thanks for everyones help and advice.

The Captain
Try watering and feeding from the bottom. Put the pots in trays or something that can hold at least 1/2" of water, set them in there for an hour, maybe more, and the soil should wick it up just fine.

Capillary action, in action.
 

Cappy

Active member
I use sand in my soil mix, so he could scrape it off, save it for the next batch of soil mixing and apply fresh sand after watering. Sand is very cheap.
 
Ya sand is very cheap. Ideally I would like to scrape off the sand each time I water and replace it with fresh sand each time. I have never had any pests before, in any of my grows. Anyone know what introduces gnats into a grow? I would think they would have to be brought via soil or maybe from a human. I used MG organic soil from a post from Blazeoneup about the soil mix he uses, maybe the MG soil had them in there?

Thanks for all the comments and input,

The Captain
 
Too much sand sitting on top can smother the surface roots and retain too much moisture. Don't overwater and allow soil to dry between waterings. Overwatering promotes gnat reproduction. Re-using the sand is a bad idea unless you sterilize it between applications.

If it is gnats, either a poison like pyrethum or Gnatrol, or a dish of vinegar with a bit of dishsoap added. The gnats like the vinegar and the dishsoap prevents the gnats from escape. They can't climb out of the dish since surface tension is lowered. (too slippery) They drown. Those yellow strip poisons work well too.

Water from the bottom? As long as it's not an every day thing. Bad idea over the long haul.
 
S

SeaMaiden

sand, porous?
Yes. Adding it to a soil mix makes it dry out much more easily/quickly. Sandy soils are well known for their inability to retain water. Porous. Look up some methods for lightening heavy soils, adding sand is one of them.
Too much sand sitting on top can smother the surface roots and retain too much moisture. Don't overwater and allow soil to dry between waterings. Overwatering promotes gnat reproduction. Re-using the sand is a bad idea unless you sterilize it between applications.

If it is gnats, either a poison like pyrethum or Gnatrol, or a dish of vinegar with a bit of dishsoap added. The gnats like the vinegar and the dishsoap prevents the gnats from escape. They can't climb out of the dish since surface tension is lowered. (too slippery) They drown. Those yellow strip poisons work well too.

Water from the bottom? As long as it's not an every day thing. Bad idea over the long haul.
I respectfully disagree. Yo can grow in nothing but sand if you can keep the plant fed and watered. Sand, unless it somehow becomes a concretion, has never once presented the problems you're alluding to for me, and is known to add porosity to heavy soils.

Watering from the bottom works great, again as long as some care is taken not to drown the plants. It's the only way I water/feed my seedlings and cuts that have not yet become well-rooted, and I've been doing it that way for years. Early this year I ended up being forced to use bottom-up watering on mature plants, all the way through flower, due to aggravation of an old injury making hand-watering with a wand next to impossible. Flood the tables, leave it a few hours to overnight, drain. No problems.

I still suggest that, especially for new seedlings and cuts, bottom-watering is more desirable for lack of root disturbance and thorough saturation of the media, as this method disallows that running off the sides thing that can happen when media becomes a bit dried out.
 
Guess we'll have to disagree then, since we come from vastly different approaches to gardening.

Bummer about the nagging injury, and I mean no disrespect...but just because you have been forced to do something outside of the plant biology norm doesn't mean it's best for everybody. Especially the newbies that really should be taught proper technique, right. Me...? I'm lazy but found that simplicity is sooo much easier, and with results good enough to keep me out of the dispensaries for my wife's meds for the past 10 years.

Mixing sand IN the medium I of course agree with. But from where I sit, smothering the top of the rootball with a layer of sand is not the best of practices and I can't think of one single advantage. Retains moisture, acts like a paperweight on your soil, restricts air flow to root zones, promotes fungus and molds...

Why the need for it? Isn't it better to fix the cause of an issue rather than suffer through an unnecessary situation?
 
Hey guys,

Put the sand on 48 hrs ago and there is still a decent amount of them. When they were smaller, I put sand on them and the gnats were gone in about 3 days.

I am watering way less frequently.

How do the bombs work? Can you use them during a grow? Can you recommend a particular brand or type? Can you get them at HD/Lowes?

Will DE get rid of them completely? Would rather not use chemicals if possible. What type and brand is best?

Thanks very much,

The Captain
 

ronbo51

Member
Veteran
Why don't you get some pyrethrin and some Gnatrol. Both are organic and they work. Knock down the fliers with the pyrethrin and follow up with regular Gnatrol applications. That's pretty much it for gnats, other than the good advice to let things dry out between waterings. I don't have first hand knowledge of root aphids, but from what I read they are way harder to eliminate than gnats. They seem to come almost exclusively from traded or purchased cuts. Most of the guys that have successfully treated for aphids use pretty hard core chemical pesticides, nothing else really works. Treat and quarantine new cuts. There is an excellent root aphid sticky here. Everything you need to know.
 
you should accurately identify the pest before you attempt to treat it .could you post some pics or give a more detailed description ?
 

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