We have two hoop houses that are covered in white plastic with no heating system. The plastic mostly serves to buffer against intense winter winds which can be just as damaging to plants as the cold itself and blocks out a substantial amount of sunlight to prevent heat building up on sunny days. Additionally, the plastic blocks snowfall and ice, which allows for us to access the plants and observe them. Potted plants in these hoop houses will easily get below freezing if those are the outdoor conditions, so we do our best not to overwinter sensitive or marginally-hardy perennials in these hoops. And when it does snow/ice, like it did earlier this month, we have to be prepared to use wide brooms to push the excessive amounts of snowfall off from the inside. If we neglect to notice and address this issue, the weight of snow could easily collapse the steel frame, creating an absolute disaster. In these unheated hoops, the soil of the pots remains consistently cold and does not require much watering at all. Overwatering could easily cause root rot since the plants are not currently photosynthesizing and uptaking water from the roots. The difficult part of this equation, though, is that potted plants with saturated soil have a much greater buffering capacity against freezing than does dry soil. So prior to days when the lows will be well below freezing, we thoroughly soak the nursery stock if needed. Winter really can be mentally grueling! A lot of the decisions about watering may be rather subjective, but they are made by constant, ongoing observations.