Polystyrene strips as a potting medium
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NYEric
Well-Known Member
I've seen it before. Not for me.
I wonder if packing peanuts would work in the same way without the mess of shredding sheet styro?
Some packing peanuts are made from corn starch and dissolve.
eds
Well-Known Member
I've used expanded polystyrene in the bottom of deep pots before and really dislike it. It breaks apart too easily when you're repotting leaving little bits of polystyrene everywhere.
I think it is a mistake to assume polystyrene is non toxic to plant growth. As it decomposes it releases different gases that will be trapped in direct contact with the roots.
I tried using it and never observed any positive benefit. But all the fragments blowing around the greenhouse was a big negative.
I tried using it and never observed any positive benefit. But all the fragments blowing around the greenhouse was a big negative.
environmentally unfriendly
I don't know what you used, but polystyrene is completely inert and therefore doesn't decompose at all. At least it doesn't decompose during ages which are relevant for human beeings or orchid growing.
Therefore it is right what Stephen mentioned. It is a problem if it gets uncontrolled into the environment.
Another reason because it may not the best choice for the use in a greenhouse may be its weight. These stripes are very light and even with a top layer of something which is more heavy e.g. small pebbles which avoid floatin during watering, the pots can tip over easily. For an indoor grower like me this isn't a problem because the cache pot gives the plant pot stability.
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The EPS strips aren't really wetted by the aqueous solutions we apply, so all the "holding ability" is due to surface tension holding onto the liquid in the spaces where the strips are close to each other. Surface roughness would also play a similar role.
I doubt packing peanuts would be very effective as they are usually quite smooth and there just wouldn't be a lot of contact points.
Glass marbles would probably be better, and would certainly reduce the top-heaviness factor, but God help you if you spilled a pot on the floor!
I doubt packing peanuts would be very effective as they are usually quite smooth and there just wouldn't be a lot of contact points.
Glass marbles would probably be better, and would certainly reduce the top-heaviness factor, but God help you if you spilled a pot on the floor!
clearsky57
Well-Known Member
on this topic though - curious,,,, what ever happened to Diatomaceous rock??
I still have some from a number of years ago, where i picked a bunch up from a place up near Buffalo NY.
it is inert and tends to wick water from below, a very suitable product for those playing with hydroponic growing.
sort of gravel like in consistancy,(but lighter) and when i repot with it, i don't usually try to pull it all off the roots, and just repot up and add more... without disturbing or damaging roots.
When i finally remove it from plants i do not throw it away, rather i take the old medium, spread it out on a wire mesh rack and let the rain rinse through it and the sun beat down and naturally bleach the material....
given it is out for quite a while, i just store up the old medium and am able to re use it again.... no waste and completely recycleable It came in three sizes fine (about 1/4" average) medium (1/2"-5/8" average) and large (3/4"-1" av.) and it had a consistancy of classroom chalk for example. It is a great product for any plants that tend to want to be feet wet or maintain some moisture without being water soaked.. i also think it has a tendency to keep the root area inside pots a tad cooler, as well. I tend to use the medium size and it has really worked well for my phrags..
I still have some from a number of years ago, where i picked a bunch up from a place up near Buffalo NY.
it is inert and tends to wick water from below, a very suitable product for those playing with hydroponic growing.
sort of gravel like in consistancy,(but lighter) and when i repot with it, i don't usually try to pull it all off the roots, and just repot up and add more... without disturbing or damaging roots.
When i finally remove it from plants i do not throw it away, rather i take the old medium, spread it out on a wire mesh rack and let the rain rinse through it and the sun beat down and naturally bleach the material....
given it is out for quite a while, i just store up the old medium and am able to re use it again.... no waste and completely recycleable It came in three sizes fine (about 1/4" average) medium (1/2"-5/8" average) and large (3/4"-1" av.) and it had a consistancy of classroom chalk for example. It is a great product for any plants that tend to want to be feet wet or maintain some moisture without being water soaked.. i also think it has a tendency to keep the root area inside pots a tad cooler, as well. I tend to use the medium size and it has really worked well for my phrags..
I think it primarily faded away due to the limited supply, but one issue was its tremendous ability to absorb and accumulate residues, and there is very little that can be done to extract them.
clearsky57
Well-Known Member
Ray= i have done some tests where i take "old used" diatomite, that has been soaked, washed and set out in the sun to dry for an extended period then put in a container of nuetral water and soaked for a period, then, ran some simple tests, that didn't show much in the results.... i grow a lot of phrags in this medium, and just add new when i pot up to a larger pot.... I have had good growth, and no evidence of any toxicity,,, at least in my unscientific opinion.
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I question if the article is referring to expanded polystyrene since it is brittle and not flexible. Seems like a sheets would not emerge from a shredder without making a terrible mess. Maybe a more flexible, thin foam sheet?
NYEric
Well-Known Member
If you mean Diatomite, and want to get rid of it, let me know. Don't worry about the supply.
That doesn't surprise me.
Diatomite was known for its super-small and extremely jagged/serpentine porosity. When dry, it soaks up liquids like mad, but doesn't release them rapidly (too much surface tension holding them in place).
Short term, that's a good thing, but those jagged crevices will get clogged pretty readily, especially if allowed to dry, resulting in more accumulation near the surface.
It would have been interesting to test that rinse water, and I think if reusing the stuff, you'd be better off storing it in an excess of plain water so more and more can come out, not baking it dry.
Thin polystyrene is actually quite flexible. If I'm not mistaken, the feed material isn't more than 2-3 mm thick, and once passing through the shredder, probably compressed a bit.
I once received a shipment of wine in which each bottle was wrapped in multiple layers of the stuff.
Actually polystyrene does decompose. In a tropical environment I have experienced termites devouring sheets of polystyrene. Mold and bacteria also degrade it.
https://www.sciencedirect.com/science/article/abs/pii/S0304389421012036
I don't know if the decompression has an effect on plant growth but one thing is for sure polystyrene mixed in substrate looks like garbage.
https://www.sciencedirect.com/science/article/abs/pii/S0304389421012036
I don't know if the decompression has an effect on plant growth but one thing is for sure polystyrene mixed in substrate looks like garbage.
This from AOS that I posted a while back. It all depends on where it’s sourced. Fresh water, okay. Salt water, not okay. U.S. sources ususally salt water.
https://www.slippertalk.com/threads/gordon-rock-wool-cubes.56167/page-2#post-760597
No, as far as I know it doesn't.Actually polystyrene does decompose. In a tropical environment I have experienced termites devouring sheets of polystyrene. Mold and bacteria also degrade it.
https://www.sciencedirect.com/science/article/abs/pii/S0304389421012036
I don't know if the decompression has an effect on plant growth but one thing is for sure polystyrene mixed in substrate looks like garbage.
It isn't decomposing when termites devour polystyrene.
If I read your linked article correctly than is the research with those bacterias still limited of the conditions within a laboratory AND it works when polystyrene was the only source of carbone. Maybe one day this method will work to decompose polystyrene .... but at the moment ??
Furthermore I'm pretty sure you don't have neither termits nor those bacterias in your greenhouse or in your indoor growing area so don't worry about decomposing of polystyrene as a potting medium.
That you don't like it in any substrate ...o.k. that's your personal taste and opinion.
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