If you would like further information concerning overwintering nursery plants, call me. We also have a horticulture information leaflet that gives more detail about constructing overwintering structures. The use of clear plastic is not recommended for winter protection. Clear plastic allows too much heat to build up during the day and too much sunlight that can scald plants. Clear plastic also releases heat quickly at night.
White plastic maintains a more uniform temperature range.
Some nurserymen use regular sized greenhouse frames for this purpose. Kenny Bailey, Asst.