Rockwool for wet wall

[itilien]

Hello,
what do you think about growing pleurothallids in a vertical wall made from rockwool that is constantly kept moist by circulating water? Probably this is fully hidroponic, but it seems that you have experience with the properties of this material. There is an orchid store owner from Belgium that runs such wall and according to his posts in facebook it is working very well. In my oppinion it has 2 advantages over epyweb and 3d mesh like hygrolon - it looks much more natural and it doesn't lock the roots of the plant like hygrolon does. But I'm wandering how fast this wool will compress and become air impervious?

[katsucats]

It's probably just my ignorant opinion, but I feel like rockwool is a minor (but unproven) health hazard, so I would personally not like them to be exposed to the air in a closed room all the time. Rockwool is basically like asbestos with longer fibers that are less hazardous, but still... For this purpose, if Hygrolon or polyester meshes don't suffice, then what about New Zealand tree fern panels? It's sustainable compared to the South American kind, at least according to the marketing material.

[camille1585]

Originally Posted by katsucats

It's probably just my ignorant opinion, but I feel like rockwool is a minor (but unproven) health hazard, so I would personally not like them to be exposed to the air in a closed room all the time. Rockwool is basically like asbestos with longer fibers that are less hazardous, but still... For this purpose, if Hygrolon or polyester meshes don't suffice, then what about New Zealand tree fern panels? It's sustainable compared to the South American kind, at least according to the marketing material.

Rockwool should be handled with care when installing (especially if it's dry) but once installed the risks are minimal especially once plants are growing all over it.


As to the original question, I recall that someone posted about pretty much the exact same setup idea some time ago and I think there was some good information in the replies. I'll see if I can find that thread again.

[Ray]

Rock wool is a glass, so is more like fiberglass than the acicular mineral, asbestos. Yes, it is still a potential hazard, but neither is hazardous just sitting there. It is only when it is worked that microscopic particles become airborne.

You would need some sort of container for rock wool mini-cubes or the loose batting; it is not mechanically self-supporting. In fact, they can collapse under their own weight when saturated.

The trays of preformed planting cubes might be rigid enough, but the root systems will penetrate those, which is something you didn’t want to happen.

The Epiweb/EcoWeb walls worked fine with tropical plants, as did the Hygrolon/AquaMat. when I was selling out my inventory be moving, my entire AquaMat stock went to a guy who built such walls for offices and malls. He has a rack of dowels that he laid the fabric on, tucking it between them to shape it into a series of “waves”. He then flattened the waves upward and sewed them in a series of vertical lines, forming pockets to hold the plants.

[itilien]

Hi, it's been a while, but the last time for some reason I wasn't able to log in in the forum for at least a week, and was not able to write in the thread, so later I forgot about it

For Ray - here we are talking for rockwools slabs, not mini-cubes. The slabs are 1000x150x75mm. Unfortunately the guy's fasebook page was hacked, so the pictures/videos are gone. The slabs are hanged on some metal hooks horizontaly on top of each other without gaps between them. So, the wall is 1m wide, 7.5cm thick wall. I don't remember the height, but it was probably about 2m. The water is circulating with quite a strong flow.
I contacted the guy and asked him few questions. He runs this wall for 2 years, if not more. He uses mycorrhizal inoculant. The wool has still not degraded and the plants love it. Mostly pleurothallids, but other non-orchids too. And it somehow works, despite that the wool is saturated all the time.
I spoke with another guy to discuss why this works and he had a theory. He supposed that the problem of constantly wet roots is not that they cannot handle the wetness, but it is the formed (probably anaerobic) conditions which are good for bacterial growth, and this is what the plants cannot handle. So he speculated that when growing them in the wet rockwool wall, the roots goes inside the wall, where there is constant flow of fresh and aerated water, which doesn't allow bacterial growth and the roots are fine even constantly wet. Also all the algae and slime is just on the surface of the wall and doesn't bother the roots. Other benefit is that the leaves stay dry.
However, I'm still not convinced that the rockwool will not degrade and fall apart in let say 3-4 years, but at least it won't be impossible to get the plants out from it.

[Ray]

The slabs are pretty sturdy, but Grodan makes a plastic rack to accommodate the 1.5" cube or round blocks on one side, mini-cubes on the other, too:



Seems to me that some targeted drilling for water flow could make that work nicely. They're intended to be flat in standard nursery trays, but with an open mesh cover to hold everything in until roots do, it would probably work great. (I may have to experiment.)

I suspect there is some validity to the bacteria theory, but I still think the "tailoring" of the roots to the environment is the biggest factor for success.

[itilien]

I plan to make very small tank - about 50x40x25cm, and I already have the slab, so I'll split it in half in length and thickness to get 3.5cm wall. Maybe I will use a 8mm PVC board on which I will glue grid of plastic wall plugs and will stick up the wool on them.