Beginner Gardening: Question about lining homemade wooden planters, 2 by RickCorey_WA

RickCorey_WA wrote:
I line some of my raised beds with plastic from the heavy plastic bags that compost came in.

Otherwise, water evaporates much too fast from the corners, and even from soil near the edges.

My walls are just concrete paving stones stood on end. It turns out that water or water vapor passes easily through 3/4" or 1" of concrete - or maybe it is the4 cracks between each paver that lets the soil dry out so fast.