One of my neighbour face same problems with the Australian native violet spread on the ground covered with round leaf for this they consult with Gardening North Side ( http://www.gardeningnorthside.com.au/landscaping-north-shore/ ), garden renovation and maintenance company. They provide guidance regarding proper flourish of your garden

 That wouldn"t be a problem for me, I am trying to get native violet to naturalise throughout the shady spots in my garden, for this purpose, as a mulch and a ground cover. They don"t use much water & are shallow rooted so I think they would be good as a mulch