The low tonight is forecasted to be 28 F. In preparation, we placed clear plastic over each row. This type of plastic is not vented. Therefore, one must be very careful to watch the temperature inside the tunnel when there is direct sunlight. Although we made it through last night, tomorrow morning will be the real test! UPDATE: After the cold night of Tueday morning--the tomatoes made it through fine. However, it didn't get as cold as predicted. We found it difficult to manage the low tunnels when the sun was out during the day. Growers should be very careful about clear plastic tunnels without vents. The tunnels can get very hot.
Clear plastic low tunnels over the tomatoes in the high tunnel.
Note that there are no vents. Care must be taken to vent low
tunnels if necessary. This can be done by opening the ends.
The ends would then be closed again well before nightfall.
(Click image for larger view)
The next morning, condensation can be seen inside the low
tunnels. This indicates that the temperature inside the low
tunnel is higher than outside the low tunnel. The temperature
reading at 7 a.m. inside the low tunnel was 42 F, outside the
low tunnel (inside the high tunnel) it was 35F. The temperature
at 9 a.m. was 73 F inside the low tunnel, outside the low
tunnel 58 F. (Click image for larger view)