I read that having an open (directly to earth) floor may cause problems in a greenhouse. So I was thinking of using a foil/barrier plastic to keep the humidity out. On top of that I was thinking of putting a layer of lime plaster or loam/clay plaster to regulate the humidity and give a walkable surface. Or a combination of the above with straw and cement. The plants will be in pots. Anyone suggestions?
work in greenhouse with mixed media floor. They have a concrete and rock foundation. It has drainage lines for ease of water flow due to watering or rain pooling. Find more issues with moss and or fungus on floors than humidity issues. Also with weed control. So it depends on how you want to treat the surrounding plants and surfaces to control potential problems such as insects and other critters.