Managing Snow and Ice With Greenhouses and High Tunnels (1/22/16)

— Written By Barclay Poling
en Español

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 Aimee Lewis

“Excessive weight of snow and ice can cause damage or even destroy greenhouses and high tunnels. Ice and snow together add significantly more weight than snow alone.

Jeremy Pickens, Alabama Extension horticulturist, points out that greenhouse load capacities differ from structure to structure, so it’s difficult to predict exactly how much is too much. The design, amount of supporting bows, and gauge of metal influence the load capacity of a structure.

“High tunnels can be especially prone to damage because they are made of inexpensive materials and are unheated. Roofs with greater pitch (Gothic arch or modified Gothic arch) can slough off snow easier than Quonset-roofed structures that have a very slight roof peak.

“Your greenhouse or high tunnel manufacturer may be able to provide additional information on the load capacity of your greenhouse or high tunnel,” Pickens says.

For heated greenhouses, double poly layers can be deflated to allow snow and ice to come in closer contact with heat being lost through conduction. This heat can increase the melting rate of snow on a structure.

Steve Fellows, owner of Techne Structures in Mobile, suggests turning up the heat in the greenhouse to enhance melting. The cost of the extra heat is less expensive than the cost of damage caused to the structure.

Fellows also recommends gently removing snow that sticks. The morning sun melting just one side of the structure can cause a weight imbalance. Use the extended handle of push brooms and gently pull the snow off the roof.

“A piece of PVC pipe with a tennis ball mounted on the end can also be used to gently knock snow loose on the underside of a structure. This is especially important if your plastic is loose and pockets have formed from sagging. Start early to remove snow before the load is unmanageable,” Pickens notes.

For unheated structures, Bill Mathis with Atlas Greenhouse in Alapaha, Ga., recommends using 2×4 or 4×4 lumber wedged between the ground and purlins or bows. This gives extra strength to the structure and is a useful technique in high tunnels because they are unheated and designed with less structural support.

According to Mathis, if support columns are not an option and you face an emergency situation, a last resort is to cut the plastic. Losing the crop is less painful than incurring the cost from damage or destruction of a structure. You can find more information from Kentucky State University at

“Remember that your safety is more important than any structure. Stay safe and use good judgment when on roads or working around ice and snow. Do you have additional information or experiences that you would like to share? If so, we would like to hear from you at,” Pickens says.