That's what I'm calling it...Inground Container Gardening. If the soil in your yard is like mine - clay and rock - then you understand. When you manage to dig a hole big enough to plant something, you find the hole itself could double for a clay pot or plastic bucket. Ugh!
Soooo...I abandoned the trench idea for the blueberry plants. (I'd still be digging) And went for the container gardening method. For the blueberries we dug holes larger than required, filled the holes with acidified potting soil, put in the plant, watered well, and mulched with sawdust left behind by the chainsaw. Photos to follow.
Boy, do I need a bath.