Hi Youri
I think I have the same dilemma.
Current photo:
http://www.meinfotograf.com/_privat/IMG_7132.JPG
I think the Spaghnum is getting too high and overgrows my Darlings. The moss is very high, around 10-11 cm.
So, should I cut it down? I think to replant the Darling into fresh peat or a very mineral soil.
Cheers
Wolfgang