Help!...Got a customer who wants an estimate for mulch around several small pine trees. There's grass growing pretty much all around right up to the trees. Is it better to spade the dirt and grass under or would some grass and weed killer work ok, before you put weedblock and mulch down? Also how do you all charge for seeding and strawing?....by the square foot or what? And how much do you charge? Thanks for any help.