I use the green coated wire. A friend and I mounted all the broms this AM using the wire and applying directly to the tree. I don't like having another medium between the tree and the plant (orchid or brom) as it tends to rot and slip. I also use this method with staghorn ferns. However I do place a bit of coconut tree fiber in the top where there is a gap. We did actually just place several in the crook of an oak tree with any tie-down as the tree is so large.
Debi
