Winter places greater pressure on every part of a commercial greenhouse. Heating systems run longer, ventilation strategies change, snow and ice add structural loads, and small gaps or equipment faults that seemed minor in warmer weather can become costly. For growers, 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 in harsher conditions.
A thorough inspection before severe weather gives teams time to fix problems before they affect production.
Inspect the structure and envelope first
Wind, snow, ice and temperature swings can expose weaknesses that are not obvious during the growing season. Operators should walk the greenhouse inside and outside and check framing connections, doors, vents, glazing systems, poly coverings, seals and other exterior components for damage, looseness or wear. Snow and wind requirements vary by location and greenhouse design, so structural maintenance should follow the building’s intended design and local requirements. If structural condition or winter loading is a concern, the greenhouse manufacturer or a qualified professional should be involved before the first major storm.
Areas where air or moisture can enter deserve particular attention. Damaged weather stripping, aging seals, loose panels and gaps around doors or vents can increase heat loss and make environmental control harder. For polyethylene-covered houses, the covering should be checked for punctures, tears, looseness or deterioration. Inflated double-poly systems should also be checked to confirm the inflation system is working properly.
Service heating and controls
A heating problem in July may be an inconvenience, but a heating failure during a January cold snap can become an operational emergency. Before temperatures fall, growers should inspect the entire heating system and complete manufacturer-recommended service. Boilers, unit heaters, radiant systems, pumps, fans, thermostats, sensors and distribution equipment should all operate as intended.
The winterization checklist should include inspecting heating equipment for visible wear or operating issues; checking thermostats and environmental sensors; testing circulation and horizontal airflow fans; confirming vents and louvers open and close correctly; inspecting control systems, alarms and backup systems; checking fuel supplies or delivery arrangements where applicable; and reviewing generator or emergency power procedures.
Protect efficiency and airflow
Environmental control in winter 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 conditions the crop needs while operating the greenhouse as efficiently as practical.
The building envelope should be checked 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. Where installed, retractable energy curtains or thermal screens should be inspected, including curtain material, drive system, cables, motors, sensors and controls, before nightly use.
Some growers add inflated polyethylene over polycarbonate or glass sidewalls and gable ends in autumn for extra insulation. Where appropriate for the design and operation, this seasonal layer can reduce heat loss without permanently changing the glazing. Equipment and storage areas should also be kept from disrupting airflow or heat distribution; benches, stored materials, equipment or temporary barriers can cause inconsistent temperatures even when a heating system is operating correctly.
Plan for snow, ice and emergencies
A commercial winter plan should cover more than routine maintenance. Teams should know 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, and doors and emergency exits should remain accessible.
In snow-prone climates, dedicated gutter snow-melt piping beneath the gutters can operate as a separate heating zone when snow or ice is present. Supplying heat where melting is needed may allow energy curtains or blackout systems to stay closed instead of being opened to let greenhouse heat reach the roof and gutters, helping maintain the insulating layer while managing accumulation. Snow removal should always follow recommendations for the specific greenhouse design. Improper removal can damage coverings or structural components, and unnecessary activity on or around a snow-loaded greenhouse can create safety risks. Operators should understand the snow and wind conditions the structure was designed for and have a response plan for unusual weather.