2 unrelated questions: rock wool and plant walls

[Undergrounder]

The plant wall is based on a system by some famous French landscape architect/designer/artist/thingamybob. His website is ici. I love them, absolutely stunning. Unfortunately they don't work here in Aus because our climate is too dry and they lose moisture too quickly.

You would need to pick orchids that can handle constant moisture for a start, and you'd fill it out with other epiphytic ferns and such. I've toyed with a simpler idea of just using a lightweight mesh over coconut husk/coir and tucking all the plants in and watering with the hose. Another key thing you need to do is use feature plants that are more or less monopiedal, or at least ones that won't dominate the other plants and take over.

Keep us posted on how you go!

There's a similar idea already here, although not as complex.