Removing moss from Brass Buttons (Leptinella squalida) groundcover
I have replaced the lawn in my yard with Brass Buttons groundcover. Unfortunately, weather conditions last winter has left if overrun with moss. In a small area I can dig out the moss with a fork, but this year there is far too much for that approach. One can find many brands of lawn chemicals with moss remover. Would these be safe for use with the groundcover? If so, how bad are they from an environmental standpoint?
Moss competes well with many plants in our environment including turf or low groundcovers, as you are discovering. I am currently allowing the moss to take over groundcovers in the shady, damper parts of my landscape. It looks great in my opinion.
To encourage the other plants to dominate, give them enough sunlight, and summer watering. Sometimes soil ph needs to be adjusted, or fertilizers used, much the same as recommended for turf. See the details in this article from Oregon State University's Gardening Tips. "If you mind moss, get on board with preventative measures": http://extension.oregonstate.edu/gardening/2017/04/if-you-mind-moss-get-board-preventative-measures
Read any lawn treatment product labels carefully, and don't use one that mixes purposes. Check a spot to see how your groundcover responds. Anything with "weed killer" is likely to kill your non-grass groundcover plants.
Again, see the article. Killing the moss you have won't truly fix your problem because it will just return. Work on discouraging it, or living with it.
A slightly different angle to deal with moss is to grow taller plants that will cover or shade it out. Heathers, ferns, and Arctostaphylos uva-ursi are possibilities height-wise. You'd have to choose plants also based on light conditions, soil type/drainage and personal preference.