What is the best way to replace a lawn with bark, to make a bush garden? ?
It would depend on the time between you killing the lawn & plant any new plantings. You can use a total vegetation killer first then remove as much as you can of the dead grass. You can use a weedblock material(some ppl use old newspaper) then put down your new mulch on top. The mulch does need to be at least 2″ deep, too thin then weedblock shows thru & weeds can come thru easier. I would wait several months before planting any new plants in the new beds. If you go using the plastic route it will take good deal longer to kill. Since it is winter it will also depend on the type of grass you have. The warm season grasses are dormant now so they might not die as well & harder to tell.