Live Sphagnum moss, while making a wonderful addition to many orchid composts, is neither cheap to buy nor particularly easy to obtain. Having bought some from Laurence Hobbs I wondered if I could pick out some of the best bits and grow it. I didn’t have any idea of the conditions it would require other than knowing it grows wild in bogs in Britain.
I bunched some nice green strands of moss in my hand as if they were a posy of flowers with all the heads together. This first bunch I put upright in a four inch deep clear plastic container, outdoors, in the shade, filled it to the brim with rain water and left it to its own devices, only adding more rainwater if the level dropped. I filled another two of these deep plastic containers and put one in the intermediate house and one in the cool house, likewise topping up with rainwater when necessary.
Then I filled several ordinary black plastic plant pots with moss and placed half in a shallow tray of rainwater in the cool greenhouse in a bright position, the other half I put in a similar shallow tray of rainwater and put them in a shady position in my intermediate greenhouse.
Both these trays had something else in them: a ceramic atomiser that I used during the growing season to provide humidity. They were switched on automatically for six hours during the middle of the day, and they raised the water temperature by a degree or two and gently circulated it while producing a very fine mist.
All the moss grew, but it was the moss in the tray with the atomiser in the intermediate house that grew really well. I have decided that the factors most important in determining the growth rate of moss are temperature and gentle water movement.
I have cropped some of the moss – just cut off the top with scissors as if I was mowing a lawn, used the lower parts of the strands, and re-planted the top four inches, this time in plastic mesh pots. It is growing away nicely.
I was talking to Peter White about sphagnum moss and he says that this is the way it is harvested in New Zealand. There, the top few inches are mown off and saved, the moss beneath is cropped, then the tops are put back to re-grow.