I hate carpet moss, especially in my pygmy Drosera pots. I usually avoid its appearance by making sure all my potting media are well rinsed, removing all trace nutrients that would encourage their growth. I've mentioned how I let the weather of the season do my work, by pre-preparing my pots well in advance and letting the season's rains leach through the pots. In the winter all is frozen and I dont have this opportunity. The water in the winter down cellar is close to freezing, and it numbs the hands when wringing out the peat. As a result I do not rinse as well as I would like, with the predictable result that in my pots of sown winter gemmae, mosses sometimes find a home. Moss growth is announced by a green or brown discoloration that lies on the surface. Early and repeated spraying can leach this out, but if not successful moss will soon cover the pot and begin choking out the small gemmaeling plants which have trouble competing with the moss.
Here is a way to remove the moss without total transplant. Pygmy Drosera resent disturbance due to the fine hairlike roots which are easily damaged.
Make sure the pot is good and wet. You need to make a cup shape with your hand to catch the top of the root ball when you knock it out of its pot. Remember making sand castles with a bucket of wet sand turned over? A similar effect apples here. With care, the entire root ball will esaily slide out of the pot. The surface moss will prevent the rossets from getting soiled. Don't sneeze, and don't squeeze!
If the mix has eroded out of the pot (as is often the case) dropping the growing surface below the pot rim, add some new mix to the bottom of the vacant pot, enough to bring the new level about an inch above the rim. Pluck the root ball back in the pot, and go rinse your hand before it dissolves into mush, heh heh.
You now have before you a mossy mound. Using great care, you may now begin the removal of the moss. It will come out easily since you can now get at the base of the mosses. Close to the rosettes you must have a gentle touch. Sometimes I lightly pin the rosette with a finger as I tease the moss away from beneath it. The moss sheet tears out in nice plugs, leaving nothing behind but clean substrate with the plants sitting now a bit above the mix. If the plants are summer sensitive, I leave them on their root stilts since this is how they are often found growing in habitat. For the other species I replace fresh mix, working it around under the plants with a flat tool.
When finished, there will be a clean pot of lovely plants now sitting on a bit of a mound, the better to see their amazing flowers.
This protocol works well for all other overgrown species as well, of course. But with the other Drosera species, root sensitivity is not such an issue, and I generally transplant all my Drosera annually in the spring into fresh mix.