Commercial greenhouses face added strain in winter. Heating systems run longer, ventilation strategies change, snow and ice increase structural loads, and small gaps or equipment problems that seemed minor in warmer weather can become costly. Winterizing is not only about keeping the greenhouse warm; it is about reducing downtime, protecting crop quality, controlling energy use and ensuring structures and environmental systems perform under harsher conditions.
Inspect the structure and envelope first
The structure should be among the first areas checked. Wind, snow, ice and temperature swings can expose weaknesses that are not obvious during the growing season. Growers should walk the greenhouse inside and outside for damaged or loose components, including framing connections, doors, vents, glazing, poly coverings, seals and other exterior parts. Snow and wind requirements vary by location and design, so operators should understand how climate-adaptive design affects structural performance in their region.
Air and moisture entry points deserve attention. Damaged weather stripping, aging seals, loose panels and gaps around doors or vents can increase heat loss and complicate environmental control. For polyethylene-covered houses, check the covering for punctures, tears, looseness or deterioration. Inflated double-poly systems should be checked to confirm the inflation system works properly. Where structural condition or winter loading is a concern, involve the manufacturer or a qualified professional rather than wait for a major storm.
Service heating and environmental controls
A heating problem in July may be inconvenient; the same problem during a January cold snap can become an operational emergency. Before temperatures drop, inspect the entire heating system and complete manufacturer-recommended service. Boilers, unit heaters, radiant systems, pumps, fans, thermostats, sensors and distribution equipment should operate as intended. The checklist should cover visible wear or operating issues, thermostat and sensor operation, circulation and horizontal airflow fans, vent and louver movement, control systems, alarms and backups, fuel supplies or delivery arrangements, and generator or emergency power procedures.
Environmental controls need attention because winter management is rarely about heating alone. Humidity, airflow, ventilation and temperature interact. Reducing ventilation too aggressively to conserve heat can create humidity problems, condensation and uneven growing conditions. The aim is to maintain the crop's required environment while operating as efficiently as practical. Heating is often one of the largest winter operating demands, making small efficiency problems worth finding early.
Reduce heat loss and protect airflow
Inspect the building envelope for escaping conditioned air. Doors that do not close properly, worn seals, gaps around penetrations, damaged glazing and poorly maintained vents can all make heating systems work harder. Retractable energy curtains or thermal screens should also be inspected where installed, including curtain material, drive system, cables, motors, sensors and controls, so problems can be corrected before nightly use. Some growers add inflated polyethylene over polycarbonate or glass sidewalls and gable ends in fall for an extra insulating layer; where appropriate, this seasonal step can reduce heat loss without permanently changing the glazing system.
Equipment and storage areas should not interfere with airflow or heat distribution. A heating system may operate correctly yet produce inconsistent temperatures if benches, stored materials, equipment or temporary barriers disrupt air movement. Winter preparation is also a time to review whether the greenhouse is still operated as originally designed. Production layouts, crops and benches change, and structures are expanded; environmental equipment that suited the original operation may need adjustment as the business evolves.
Prepare for storms and snow
A commercial winter plan should go beyond routine maintenance. The team should know what happens when severe weather arrives and who monitors snow accumulation, heating equipment, alarms, backup power, vents and other critical systems during storms or extreme cold. Gutters, drainage paths and areas around the greenhouse should be kept clear where practical so melting snow and ice can drain. Doors and emergency exits should be inspected to ensure winter weather will not prevent access.
In snow-prone climates, growers may consider dedicated gutter snow-melt piping installed beneath gutters. Such a system can operate as its own heating zone and be activated only when snow or ice is present on the roof or in the gutters. By supplying heat where melting is needed, growers may be able to keep energy curtains or blackout systems closed rather than opening them to let greenhouse heat reach the roof and gutters, helping maintain the insulating layer while managing snow and ice.
Snow removal should always follow recommendations for the specific greenhouse design. Improper removal can damage coverings or structural components, and unnecessary personnel activity on or around a snow-loaded greenhouse can create safety risks. Operators should understand the snow and wind conditions the structure was designed to handle and have a response plan for unusual weather.