Sponge Rock

[Carkin]

Does anyone use just Sponge Rock as a potting medium?

I like that it doesn't break down like Sphagnum Moss does and I am under the impression that it holds more moisture than bark mixes, so I thought that maybe I can use it straight for my Oncidiums.

What do you think?

[jpyerry]

I was under the impression that sponge rock is just another name for perlite. If this is true, I would imagine that almost everyone uses sponge rock as a medium on at least one plant if not more.

[Carkin]

Originally Posted by jpyerry

I was under the impression that sponge rock is just another name for perlite. If this is true, I would imagine that almost everyone uses sponge rock as a medium on at least one plant if not more.

I think that it is the same thing. The bag that I have is made up of medium size chunks. Do you mean most people use it alone...not mixed in with bark?

[Fishmom]

I have seen a member of my OS who uses it alone, but it is so light that anchoring the plant can be a problem. It doesn't pack down like a bark mix, and it doesn't have the weight of LECA or rock. It might work better with a pot clip of some sort.

[Carkin]

Originally Posted by Fishmom

I have seen a member of my OS who uses it alone, but it is so light that anchoring the plant can be a problem. It doesn't pack down like a bark mix, and it doesn't have the weight of LECA or rock. It might work better with a pot clip of some sort.

Good point! My Oncidiums are top heavy too. I wonder if I can mix it with Lava Rock?

[jpyerry]

Originally Posted by Carkin

I think that it is the same thing. The bag that I have is made up of medium size chunks. Do you mean most people use it alone...not mixed in with bark?

No, I mean mixed in with other components. I can't imagine why anyone would want to use it alone, every time you water half your media would float away.

[Ray]

My very first experiments that led to the development of semi-hydroponics utilized coarse (~3/4")
sponge rock as a medium, and it worked fine.

Unfortunately, over time it crumbles, forming a sludge in the bottom of the pot.

[11Orchid126]

I use the very large stuff. The small stuff fills in too many spaces and cuts off air to the roots and makes the medium too dense. To my knowledge it doesn't hold that much moisture.

[orchids4me]

I think I recall Bolero uses it on Catts. They need to dry between watering so it works for that particular orchid in his area of the world and environment.