Rock wool for semi-H?

[jkofferdahl]

I avoid the use of rock wool for several reasons. First, orchids prefer acidic conditions while rock wool creates a base environment. Second, it's environmentally a nasty substance that sits in landfills and takes decades to break down. Finally, the dust from it - and a new package is going to be dusty - is about as good for you to breathe in as are coal or silicon. There are much safer and more environmentally friendly ways to maintain moisture for orchids.