About High Tunnel Cold Frame Greenhouses ABOUT AGRICULTURAL HIGH TUNNEL AND COLD FRAME GREENHOUSES High tunnel agricultural greenhouses are the basic type of field greenhouses used to extend crop production and are generally very low tech. Our agricultural high tunnel greenhouses can be easily installed and high tunnel. Greenhouses are available in a number of sizes. High tunnel agricultural greenhouses are basically crop covers and are covered with 4 year greenhouse poly. Agricultural greenhouses adapt themselves to many different crops. The agricultural greenhouses are normally Quonset type though Gothic high tunnel structures are popular in snow load areas. Vegetable high tunnel greenhouses do not require crop support and are very good for vegetable propagation. In many cases, our high tunnel greenhouses and cold frame greenhouses are used year around in modest climates. Many of our agricultural high tunnel greenhouses can be built in such a way that upgrades for heating, ventilation, etc. can be added without modification to our high tunnel greenhouse as well as the cold frame greenhouse. For inexpensive ventilation, both our high tunnel and cold frame structures are available with rollup sidewalls, either motorized, or manual if no electricity is available or is not required when installing high tunnel greenhouses. We recently introduced a high tunnel greenhouse that actually travels on skids for research centers, seed companies, agricultural testing facilities, where the high tunnel greenhouse as large as 30 x 100 feet can be moved throughout the field. Insect screen is also a popular covering for high tunnel and cold frame greenhouses. When using both poly and insect screen, they can be removed at the end of the season. Often insect screen is popular with institutions and government agencies for use on these agricultural high tunnels. Insect screen coverings will protect against large flying insects to insects as small as white fly and thrip. However, it should be noted the more dense the insect screen the less the air flow and the resulting high temperatures within the structures.