Interesting comments here. Don, I see no reason for wanting a concrete floor, surely there is enough concrete in the world?
That is a problem I have with greenhouses and mine has a concrete foundation for the wall, no way around that unless your garden is incredibly sheltered. Whereas my polytunnel has simple foundation tubes, banged in the ground. I could relocate it quite easily, as we did in 2013 to here.
My cedar greenhouse works well with a soil/compost floor, see January update. Freed, I would go for soil. I think people worry about weeds but mulched, undisturbed soil grows so few, and having non-concrete floor gives extra growing options, and less watering than for containers.
The greenhouse costs far more money, but is warmer and has less pests.
