In northern growing environments, winter can be very hard on greenhouses and the owners who maintain the structures, says Brent Bates, director of safety services and loss control at Hortica®, a brand of the Sentry Insurance Group. Heavy wet snow accompanied by wind can do major damage to greenhouse structures.
Bates’ advice to owner operators of greenhouse growing facilities is to know their structure’s design specifications inclusive of the wind and snow loads. This information can be obtained by contacting the greenhouse manufacturer. For local code requirements, contact their governmental facility or the National Greenhouse Manufacturers Association (NGMA).
Prior to a predicted major snowfall, the heat should be turned up so the roofs and the gutters are able to melt the snow immediately when it hits. “If you wait until the snow begins to accumulate before turning up the heat, it may be too late,” Bates says. “Once the snow piles up in the gutter and heavy wind follows, the stress is such that the greenhouse will begin to fail. Shoveling the snow from the gutters is very dangerous and not recommended. If one greenhouse collapses in a gutter-connect range, the others will be damaged as well.”
There are some ideas practiced in the industry that reduce the chance of collapse. Bates says growers need to have additional bracing available at all times to place under the gutters. They should also consider the installation of steel cables, also referred to as “dead men”, to help in keeping the structures from swaying in the wind. As stated earlier, once the greenhouse begins to lean and additional snow is added a domino collapse is likely.
Per Bates, growers should evaluate their greenhouse structures periodically to determine how much risk a heavy snow could pose and what types of repairs are needed. To start, he recommends looking at the greenhouse’s welds and seeing how they have held up over the past winters. Growers should log all maintenance issues and refer to it when making repairs. Bates added, “Maintenance personnel should take a good look at the structure to see if it has in anyway shifted. They should also look at the connection points to make sure the nuts and bolts are secured.”
Preparing a greenhouse for winter is not a one-person job. According to Bates, growers should involve their employees in preparing the greenhouse for winter. He recommends creating a snow maintenance log so all work is tracked and specific tasks are assigned to employees. For example, if an employee has experience reinforcing the structure, manager should assign them to do it before winter.
“Growers should plan ahead and prepare for winter throughout the year. By planning ahead, it gives the grower time to do the proper repairs and make sure every base is covered before the first snowfall,” says Bates.