I’m with Lyanda on this; grass by its very nature is tough, durable stuff. (I was just reading the other day how grasses evolved an entirely different chemical pathway for photosynthesis that, while less efficient from a solar energy point of view, is much more thrifty with water – hence the ability of grasses to grow in arid conditions that would kill lesser plants.)

So, they’re tough cookies – but not indestructible. If you don’t want to dig the grass out first (and who would?), burlap mulching to get rid of it still works fine, given time. But you can help the process along greatly:

- Play barber: mow/weedwhack the grass you’re going to cover as low as you can first.
- Cover it with a layer of mulch / chaff / grass clippings / compost.
- Put the burlap bags on top, but (and here’s the critical step!) take an extra moment to put a layer of thin cardboard, a sheet of kraft paper, a few brown paper bags, or even some sheets of newspaper into the bags. Make sure that it goes all the way into the corners.
- Stake the bags down thoroughly and make sure they’re slightly overlapped. Mulch or bark over the top if you prefer for the aesthetics.

The layer of cardboard/paper in the bags will give a few extra months of complete light and water blockage, and make it less likely the grass blades can sneak their way through. By the time the paper dissolves naturally away, the grass should be long gone.

Let us know how it works for you!

-David / Seattle Burlap