2x? "sifted" media? Treat media before using?

[nogreenthumbs]

I've got 2 questions.

1. I keep seeing references to "sifted" media.

What's the sifting process/purpose?

Is this just the process of putting a large batch of media through screens of various size in order to separate them into small, medium, large?

2. Should I be doing anything to media before using it. I've seen some allusions to processing of some sort before use. I've got some mix that I got from a local orchid shop. It's orchiata, charcoal and perlite. I bought a bag and was given 2 smaller bags for free. The larger bag has a TON of dust in the bottom. I've been using the media out of the bag and then running a ton of water through the pots when I first pot with that media. I'm assuming that the prodigious amount of water that I run through is rinsing the dust out. Would you recommend doing anything else to the media, or doing something different to get the dust out or does it matter.

Most of the pots that I'm using are clear plastic orchid pots with slots on the sides and lots of slots in the bottom.

[Egrigby]

Hi Steve,

I can answer about the sifting in relation to cheaper brands of orchid media. Miracle Grow Orchid Mix puts some kind of peat, or potting soil in with the bark. I believe they do this in the attempt to make it good for "all kinds of orchids" They also mix the size of the chips.

So in the bag you have teeny tiny chips mixed with huge chips, as well as a lot of dirty dust. It's a recipe for root smothering. The dirt coats the roots, and the small and large pieces fill in all the holes causing surface tension to allow water bubbles to form around the roots and suffocate them.

So if you buy cheaper stuff, make sure to do a basic sift to get the dirt out, run your fingers through to make sure there isn't too big a size difference in bark chips. You should be fine as long as you are watering properly and have a well ventilated pot. I use a wire mesh kitchen strainer, and then just lay it on newspaper to check the size.

I have never heard of anyone having to sift Orchiata, it's a premium brand and they don't use fillers as far as I know?

Non-newbie experts will chime in. I just know, my orchids do 100 times better in Miracle Grow when I sift out the dirt and dust. (Thanks to those who gave that advice.)

Elaine

[Orchid Whisperer]

Originally Posted by Egrigby

I have never heard of anyone having to sift Orchiata, it's a premium brand and they don't use fillers as far as I know?


Elaine

Orchiata is bark from a specific kind of tree (Pinus radiata). Orchiata is also treated as a brand name (there are other brands of the same kind of bark; arguably the same stuff). Like all barks, it will come in a variety of sizes after being sorted (seedling size, medium, coarse).

Douglas fir bark is another common bark used for orchids. I grow most of my orchids in Douglas fir bark. It can also be size-sorted, similar to orchiata.

[nogreenthumbs]

Thanks, Elaine.

I assume this is Orchiata that was purchase in a large amount in different sizes. This place then makes their own mix. You can buy medium orchiata with charcoal and perlite. You can buy large orchiata with charcoal and perlite. The charcoal and perlite aren't sized, so regardless of the mix, those are the same size. Only the orchiata bark is different sizes. I think the reason the one bag has more dust is because it was at the bottom of the batch when they filled the bag. The two free bags don't have dust in them.

So now I need to know what to do with the dusty stuff that I have. What I need to do to it before using it to make sure the dust doesn't cause a problem.

[bil]

I have two grades of screens, sieves.

Everything that stays in the coarse sieve I use for phals.

What goes thru is re sieved in the fine sieve, and what stays in that I use for fine root orchids that I pot. Paphs, phrags and Catasetinae.

The ultra fines go for soil mixes like for ferns.

[King_of_orchid_growing:)]

The wood dust?

Just throw that in your flower bed or under a tree.

If you're talking about the peat, same thing, throw it in your flower bed or under a tree.

There shouldn't be anything in it that would cause harm to those.

[nogreenthumbs]

OK, I don't have an outside space or gear to sift the dust out. Should I just put what I'll need in a pot and rinse the crap out of it before I use it for potting?

It should be mostly charcoal and perlite dust, I assume, both of which sound like they would not be great to be caked around roots.

[Mountaineer370]

Originally Posted by nogreenthumbs

OK, I don't have an outside space or gear to sift the dust out. Should I just put what I'll need in a pot and rinse the crap out of it before I use it for potting?

I'm a "put it in a pot and rinse the crap out of it" person. To me, it makes more sense to plant in clean media from the get-go instead of relying on just flushing the pots to rinse that dust out.

Originally Posted by nogreenthumbs

It should be mostly charcoal and perlite dust, I assume, both of which sound like they would not be great to be caked around roots.

FWIW, I don't think it would be great to inhale that stuff, either. Use caution and pour very slowly. Yesterday, I was making a batch of homemade potting mix for African violets, and when I added the perlite, a big white cloud of dust flew up. I stepped far away until it settled. I haven't used charcoal, but I'm guessing it's pretty dusty, too.

[nogreenthumbs]

Originally Posted by Mountaineer370

FWIW, I don't think it would be great to inhale that stuff, either. Use caution and pour very slowly. Yesterday, I was making a batch of homemade potting mix for African violets, and when I added the perlite, a big white cloud of dust flew up. I stepped far away until it settled. I haven't used charcoal, but I'm guessing it's pretty dusty, too.

I agree. Perlite especially, is supposed to be a type of obsidian which is volcanic glass. The make-up of perlite is something like 70% silicon dioxide. I would assume that the perlite dust will be "sharp" which would work it's way into the lung tissue. Also, back when I was doing DIY stuff around the house, anything that had silica as a powdered ingredient (grout, mortar, cement, etc...) always had inhalation warnings for cancer. Just another reason why rinsing the stuff down with water seems like a good idea.

[King_of_orchid_growing:)]

You can place the mix in a basket and rinse. That works fine.

You can hand pick pieces that are more uniform. It's up to you.