I have been rooting cuttings for several years using an open air mist-box with continous misters sun-up to sun-down. This year, I have been attempting to propagate mosses. The rooting has gone well, but within the first week or two of removal from the mist they fail. Tender new growth withers and the cutting turns black from the bottom up. I keep them in dappled shade during this transition time (still in their propagation 5oz cups), misting them several times a day.

Anyone have any ideas what could be causing these cutting to fail?