The phlox can be planted through landscaping paper, but do not us plastic as it keeps the soil damp and does not let air pass. I prefer first pulling all the weeds, then planting the phlox, then laying down newspaper four to five pages thick on the bare soil. Then cover the newspaper with a bark or wood chip mulch, but not right up to the newly planted phlox plants. I am not sure where you live, but in Western Washington creeping phlox is a great ground cover for small areas as it does not grow quickly. It needs full sun and good drainage. On a large slope you may want to use a fast ground cover like cotoneaster \"low fast\" or junipers or even hardy crane's bill geraniums. Look around your neighborhood and see what ground covers have worked for others. Keep growing, Marianne Binetti