I make raised bed walls out of thin concrete pavers stood on end - 3/4" or 1" thick, and standing 8 or 12" tall. Sometimes the corners or edges dry out too fast.
Then I tip the pavers away from the bed and lay some plastic between the pavers and the soil, then lean the pavers back into place to hold the plastic. That keeps air and water from passing as freely between and through the pavers.
I cut the plastic from big bags of soil amendments that would otherwise have been thrown away. And I keep the plastic below soil level so it isn't unsightly.
I hadn't thought of it, but it may also help with invading weeds as your tip explains. In many beds, I still have so many weeds that I can't tell if some are coming through the walls.
These are very new beds, that have never been sufficiently mulched.
