Commercial greenhouses face added pressure in winter: heating systems run longer, ventilation strategies change, snow and ice can increase structural loads, and small gaps or equipment issues that seemed minor in warmer weather can quickly become expensive problems. Winterizing is not only about keeping the greenhouse warm; it is about reducing downtime, protecting crop quality, controlling energy use and keeping the structure and environmental systems performing when conditions outside are less forgiving.
A thorough inspection before severe winter weather gives teams time to address problems before they affect production.
Start with the structure and envelope
The structure should be inspected first. Walk the greenhouse inside and out and check framing connections, doors, vents, glazing, poly coverings, seals and other exterior components for wear. Pay particular attention to weather stripping, aging seals, loose panels and gaps around doors or vents, which can increase heat loss and make environmental control more difficult. For polyethylene-covered greenhouses, inspect covering for punctures, tears, looseness or deterioration, and confirm that inflated double-poly systems are functioning properly. Snow and wind requirements vary by location and greenhouse design, so operators should confirm that components are maintained according to the building’s intended design and local requirements. If structural condition or winter loading is a concern, involve the greenhouse manufacturer or a qualified professional rather than waiting for the first major storm.
Service heating and controls before the cold
A heating problem in July may be an inconvenience; one during a January cold snap can become an operational emergency. Before temperatures drop, inspect the entire heating system and complete any manufacturer-recommended service. Boilers, unit heaters, radiant systems, pumps, fans, thermostats, sensors and distribution equipment should all operate as intended.
- Inspect heating equipment for visible wear or operating issues.
- Check thermostats and environmental sensors for proper operation.
- Test circulation and horizontal airflow fans.
- Confirm vents and louvers open and close correctly.
- Inspect control systems, alarms and backup systems.
- Check fuel supplies or fuel delivery arrangements where applicable.
- Review generator or emergency power procedures.
Balance heat, humidity and airflow
Environmental controls deserve particular attention because winter greenhouse 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 goal is to maintain the conditions the crop requires while operating the greenhouse as efficiently as practical. Heating is often one of the largest winter operating demands, so small efficiency problems are worth finding before the coldest weather.
Inspect the building envelope for areas where conditioned air may be escaping. Doors that do not close properly, worn seals, gaps around penetrations, damaged glazing and poorly maintained vents can make heating systems work harder. Where installed, inspect retractable energy curtains or thermal screens, 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 insulation layer; where appropriate for the design and operation, this can reduce heat loss without permanently changing the glazing system. Keep equipment and storage areas from interfering with airflow or heating distribution. Benches, stored materials, equipment or temporary barriers can disrupt air movement and produce inconsistent temperatures even when a heating system is operating correctly. This is also a good time to review whether the greenhouse is still operated as originally designed, because production layouts, crops, benches and structures change.
Plan for storms, snow and access
A commercial greenhouse winter plan should include more than routine maintenance. The team should know what happens when severe weather arrives and who is responsible for monitoring snow accumulation, heating equipment, alarms, backup power, vents and other critical systems. Keep gutters, drainage paths and areas around the greenhouse clear where practical so melting snow and ice can drain properly. Inspect doors and emergency exits so winter weather will not prevent access. In snow-prone climates, growers may consider dedicated gutter snow-melt piping installed beneath the gutters. It 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; this helps maintain the insulating layer while managing snow and ice. Snow removal should follow the recommendations for the specific greenhouse design. Improper removal can damage coverings or structural components, while unnecessary personnel activity on or around a snow-loaded greenhouse can create safety risks. Operators should understand the snow and wind conditions their greenhouse was designed to handle and have a response plan for unusual weather.