Hello. I'm very excited to plant a new perennial garden at a newly built house beginning early summer, Zone 6b. I've planned for several LARGE garden beds along the front walkway. A landscaper will place some boulders and plant the trees and large shrubs leaving the rest of the space for me to fill in with perennials. Here's my dilemma: I would like to plant out these beds gradually over the summer and fall. So rather than have topsoil showing, would you cover the unplanted beds with mulch (raking back gradually as the bed is planted) or is there another way or material (like astroturf?) to make the beds look less unfinished for months?