Peat moss layer in flower bed?? Totally clueless about outdoor plants. I have extra peat moss from when we had to replant our grass. Would it be helpful or detrimental to put a layer of this in my flower bed before putting mulch down? I have Bobo hydrangea, peonies, lavender, Russian sage, sedum, alyssum, dianthus, forget me nots, weigelia, boxwoods