thanks for the link , very helpful . would the dry start method work with riccia moss ? will riccia ever 'grab' onto anything ?
Yeah, riccia will attach itself to rocks. I had some attach by accident when I dry started my mosses. I don't think you need buttermilk. I just chopped up the mosses, spread them on the rock and sprayed them with water with a very tiny amount of Flourish. Something like a couple of drops per liter of water. It'll take about a week or two for them to attach. If you find that the rock or branch they're on is prone to drying out then wrap it in plastic wrap after you spray. Just make sure to unwrap them once a day for around 30 minutes.
FYI Pellia and mini pellia will can also attach to things during a dry start.
Riccia will not stay attached, if it ever does, when submerged. Also, if you keep it tied to something, you need to constantly trim it to make sure that the lower parts don't die off. If that happens the riccia will just float away. Buttermilk will smell and look funky for a while, but it should work. Make sure to aerate well!