Commercial greenhouses face a different set of operating pressures in winter. Heating systems run longer, ventilation strategies shift, snow and ice add structural loads, and small gaps or equipment faults that caused little trouble in mild weather can become costly failures. A winterization program is therefore not only about keeping the crop warm; it is a way to reduce downtime, protect crop quality, control energy use, and confirm that the structure and environmental systems can handle harsher conditions.
Operators should begin with an inspection before severe weather arrives, walking the greenhouse inside and outside for damaged or loose components. Framing connections, doors, vents, glazing, poly coverings, seals and other exterior parts all merit checks. Because snow and wind requirements vary by location and greenhouse design, growers should understand how climate-adaptive design affects structural performance in their region.
Find air leaks and covering damage
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 complicate environmental control. For polyethylene-covered houses, the covering should be checked for punctures, tears, looseness or deterioration, and inflated double-poly systems should be tested to confirm the inflation system works. If structural condition or winter loading is a concern, growers should involve the greenhouse manufacturer or a qualified professional rather than waiting for a major storm.
Treat heating as an emergency system
A heating problem in July may be inconvenient; the same problem during a January cold snap can become an operational emergency. The entire heating system should be inspected and manufacturer-recommended service completed before temperatures fall. Boilers, unit heaters, radiant systems, pumps, fans, thermostats, sensors and distribution equipment should all operate as intended.
The winter checklist should also cover thermostats and environmental sensors, circulation and horizontal airflow fans, vents and louvers, control systems, alarms and backups, fuel supplies or delivery arrangements, and generator or emergency-power procedures.
Balance ventilation, humidity and heat loss
Environmental control needs attention because winter management is rarely about heating alone. Humidity, airflow, ventilation and temperature interact. Cutting ventilation too aggressively to conserve heat can produce humidity problems, condensation and uneven growing conditions. The aim is to maintain the conditions the crop requires while running the greenhouse as efficiently as practical.
Heating is often one of the largest winter operating demands, so small efficiency problems are worth finding early. 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. Some growers add inflated polyethylene over polycarbonate or glass sidewalls and gable ends in fall for extra insulation. Where suitable for the design and operation, this seasonal layer can reduce heat loss without permanently changing the existing glazing.
Equipment and storage areas should not interfere with airflow or heat distribution. A heating system can operate correctly yet produce inconsistent temperatures if benches, stored materials, equipment or temporary barriers disrupt air movement. The pre-winter review is also a chance to check whether the greenhouse is still operated as originally designed, since production layouts, crops, benches and structures change over time.
Plan for storms, snow and access
A commercial winter plan should go beyond routine maintenance. The team 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 installed beneath gutters can operate as its own heating zone and be activated when snow or ice is present on the roof or in the gutters. By supplying heat where melting is needed, this approach can allow energy curtains or blackout systems to remain closed instead of being opened to let greenhouse heat reach the roof and gutters, helping preserve the insulating layer while managing accumulation.
Snow removal should follow recommendations for the specific greenhouse design. Improper removal can damage coverings or structural components, and unnecessary personnel activity on or near a snow-loaded greenhouse can create safety risks. Operators should know the snow and wind conditions the structure was designed to handle and have a response plan for unusual weather.