>>137415>what exactly does lining the bottom of the beds do?It keeps out ground dwelling pests like moles if it's strong enough. I never heard anyone give a better reason and in my humble opinion it's money wasted unless you have a serious gopher infestation going on. I simply filled mine up with soil from my yard; no lining or anything like that. It worked out fine; no regrets 6 years down the line.
Pic unrelated; my peas. They remained rather small this year, don't really know why. They got the same treatment they always get, and they did fine in the same spot 4 rotations ago. I suspect the cold spring over here.