I had a terrible, terrible experience with coir from which I never really recovered. I was using some of the compressed brick types that are sold by many outfits, but mine came from a local plant society that claimed 'wonderful' results. According to recommendations, after hydrating I mixed it with grit or pumice or perlite, whichever seemed most suitable. About a quarter of what I planted in it, mainly bulbs, succulents, and some general perennials, died within a year. Half went into near stasis, and just sat there, putting on no new growth, no new roots, complete zombies. The other quarter seemed happy as could be. Cyclamen rohlfsianum absolutely loved it, and grew into monsters. Narcissus absolutely hated it, and I lost most of my collection. In the subsequent repotting effort I threw buckets and buckets of the spent coir in a big heap by the compost pile. This heap was completely weed free for a couple of years, as if it was saturated with herbicide. The ground around it was weedy as ever, right up to the invisible coir barrier. That said, I still use coir. I did more research and found that orchid folks who use it have a long and involved regimen of rinsing and soaking and rinsing and rinsing and treating with epsom salts, ad infinitum. Apparently the coconut hulls come from some very salty locations, and the processors do not wash it. The rinsing regimen is not for me, thank you. Instead I switched over to MetroMix with coir (don't remember the exact number, but I like the one without vermiculite). I still mix this with grit or pumice or perlite. They do all the washing for you, most certainly test it, and pretty much have to guarantee performance or they will have a lot of BIG angry customers. Or, if you want to live dangerously, use the raw stuff and you may find you will soon have a lot more room in the greenhouse like I did. --Roy NW of Boston