Just finished installing a yard of multch, I always have gone and bought the plastic edging only to have a stake come out causing that edge pull up. I have a neighbor that has a landscape company. I saw his yard and I noticed no edging or pavers to hold multch. I asked him why, he said to just cut a line with a spade and fill that natural edge with multch. Looks much better and will be easy to fix down the road. Also add L X W X thickness to get an accurate Sq ft to get enough so you do not have to make serveral runs to Menards.