Hello, I'm thinking of trying pallet collars for growing peppers this summer. A single collar is 20cm (8 inches) in height, do you think that's deep enough?
Is it closed or open bottom? If you're just using it as a raised bed (open bottom) on top of usable soil it's fine. If it's closed, you'll want to stack a few open ones to give some more depth or you'll have short plants with not a whole lot of fruit.