The winter of 2014 will certainly go down as one of the worst in recent memory, and "polar vortex" is a term we won't forget for a while. As always, extreme winter weather can create a myriad of challenges for greenhouse growers. Michigan, in particular (the third-largest producer of floriculture crops in the U.S.), experienced record-breaking snowfall and freezing temperatures this past winter, and the Michigan State University Extension surveyed growers about the damage.

Of those who responded to the survey, 49 percent reported sustaining damage such as bending and sinking metal structures from snow load, affecting a total of 14 acres of greenhouses. Some growers, however, thwarted snow load damage by cutting greenhouse plastic to let snow fall into the greenhouse. Others heated their greenhouses to at least 50 degrees to stop snow from collecting on the roof and in the gutters, says Michigan State Extension Educator Heidi Wollaeger. But that extra heat came at a cost, at least for some growers.

"I think the statistic that surprised me the most from the survey was the large range in the increased heating costs between greenhouses," says Wollaeger. "While some greenhouses saw no difference in their costs compared to other years, others reported a 300 percent increase in heating costs. The range of costs can be attributed to many factors, including whether the business 'locked in' a fuel price prior to the season." Other factors that could be contributors to the variance in heating costs include efficiency of the heating equipment, greenhouse coverings and the age of the structure.

Dealing with the deep freeze

The extremely cold temperatures in January and February also made it hard for vegetative cutting and young plant suppliers to ship product without the plants sustaining damage. Of the growers who responded to the survey, 65 percent received vegetative cuttings that had chilling injury or were frozen.

"During the coldest weeks, suppliers or young plant producers would have been forced to delay shipments to prevent damage to their products," Wollaeger notes. These plant shipment delays affected production timing, too. According to the survey, more than half (53 percent) of growers said their scheduling was disrupted by the frigid temperatures.

However, when it comes to consumers' gardens this spring, Wollaeger doesn't think the harsh winter will have much of an effect. "Growers have been able to effectively catch up," she says.

Be prepared

While the threat of heavy snow for this season has passed, it’s always good to keep in mind the following tips for ensuring your greenhouse withstands a heavy snowfall (courtesy of John Bartok, agricultural engineer and University of Connecticut Extension professor emeritus):
  • Increase greenhouse temperature to 75°F before the storm arrives. Add an extra heater if needed.
  • Open energy screens.
  • Remove heavy loads of hanging baskets.
  • Check that all plastic attachments and furring strips are tight.
  • Check tightness of greenhouse frame and collar tie connection bolts.
  • Increase inflation pressure for plastic-covered houses. Cut sidewall plastic to allow snow in if it fills area between houses. Have poly repair tape on hand.
  • Install 2”-by-4” support posts under ridges every 12 feet in hoophouses.
Delta T Solutions has designed and manufactured customized heating solutions for greenhouse growers using hydronic (hot water radiant) heat for more than 20 years. To learn more about cost-effective in-ground bench and perimeter heating systems; high-efficiency boiler systems; and other systems that improve crop health, contact Delta T at 800-552-5058 or email