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

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.

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

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.

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.

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.

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.

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.

I put a fine screen strainer in my sink so that fines don't plug it up (Walmart). Then I put a colander in the sink, add the bark and rinse it well. You can then empty the fines into your wastebasket. If you want to sort what's left, you can. I store it in a zip lock bag after that.

Great, thanks. Yeah, it came in ziplock bags.

Before you store it in a ziplock bag, do you leave it out to dry, or do you store the wet media in the bag?

I'm sure this is open for debate. I just put it back in the bag damp. Maybe if I were storing it for months it would make a difference but, I'm usually using it fairly quickly. This is the kind of topic I generally get corrected on...and since I soak my bark before I use it, this saves a step.

Thanks

I dry mine in a brownie pan lined with wax paper. I tend to buy much larger boxes of mix now that I have more orchids though. When I use a mix with lots of dust I just tend to pick through it and take what I want out then I rinse it in a colander. or just soak it in a bowl and grab the mix out. What is left in the bottom of the bowl I throw on my outside plants. They don't seem to mind. If it's raining hard I have also flushed it down the toilet before.

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.

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.

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.

DO NOT RINSE ORCHIATA!!!

You will be washing away $$$. It is coated with dolomite (I think).

Any mineral dust (dolomite or other) is likely to be washed away rapidly when routinely watering the plant. The solubility of dolomite is quite low, therefore washing it away won't be a great loss from a mineral nutrition viewpoint.

I should clarify my post above where I said I'm a rinse the heck out of it person. I have thoroughly rinsed Hydroton (expanded clay) pellets, as they come with a lot of orange dust on them. I have rinsed a batch of small fir bark I bought, as it was dusty and had a lot of small particles I didn't want included in my media.

I use Orchiata with nothing mixed in for my Phals, and I do not rinse that. I have found that to be the cleanest stuff I have ever bought. I personally like Orchiata very much. I know others will disagree. It does dry fairly quickly in my growing conditions and, in my experience, requires more frequent watering than some other materials. Since I have a small number of plants and I enjoy watering them, I'm okay with that.

Going back to the OP. There was a lot of dust in the bag. Better safe than sorry. When I use a premium blend, I don't rinse or soak either. When I'm at the mercy of bagged product or I see a problem, as you all would do, I change my methods.

Thanks everyone. You've provided me with lots of good information.

Orchiata is composted in huge windrows, as a way to break down the pine resins that would be toxic to your orchids. (Rexius fir bark is steamed to do that, but it also softens it, reducng it's life span.)

During that process, the pH is monitored and adjusted by the addition of dolomite solutions. Some of the solution is absorbed, and some will remain as a dust coating.

A quick rinse will take away some of the coating, but will not have a significant negative impact on the absorbed stuff. Just don't soak it overnight, as is often recommended for bark.

Thanks Ray. I rinsed for a minute or two. That seemed to get the worst of it off, but very good to know about the purpose of the dolomite.