Pre-Season Greenhouse Checklist

Structural Checks and Cleaning

Wash Glazing: Scrub panels inside and out with mild soap to remove algae and dirt, which maximizes light transmission during short winter days.
Inspect Seals: Check weatherstripping on doors and windows; caulk or tape gaps to block cold drafts.
Clear Gutters: Remove leaves and debris from gutters and downspouts to prevent ice dams and overflowing water.
Sanitize Interior: Disinfect benches, trays, and floors to eliminate hidden fungal spores and pests.
Remove Shade Cloth: Remove exterior shade cloth to maximize light transmission during the shorter days of the winter season.

Test Heaters: Clean burner assemblies, check fuel or gas lines, test thermostats, and verify pilot lights or igniters.
Check Exhaust & Intake: For heaters, check exhaust stacks/vent pipe and intake air duct or ports for obstruction (birds and critters).
Check Boiler Systems: Check boiler systems for operation and general maintenance.
Inspect Energy Curtains (Shade): Check/replace fabric and energy seals, lubricate racks/pinions, and check drives.
Install Alarms: Set up a low-temperature backup monitor or alarm to alert you if heating fails.
Add Insulation: Line interior walls (especially north and east exposures) with horticultural bubble wrap to retain warmth. Check inflation systems on structures with two layers of polyethylene covering.
Check Ventilation: Ensure automated or manual vents can still open slightly on mild days to control destructive humidity.
Check Shutters: Make sure shutters are closing fully to keep excessive cold air from entering the greenhouse.

Drain Hoses: Empty outdoor lines, hoses, and water barrels to prevent freezing and cracking.
Adjust Watering: Switch to sparing, early-morning watering routines so excess moisture evaporates before nightfall.

Proper airflow and mindful watering are critical when managing low temperatures and high humidity during the colder months.

Disconnect Power: Disconnect power before touching any hardware.
Clean Lenses: Wipe LED lenses and housing using a soft cloth with a weak vinegar and water mix to clear lime scale and dirt.
Clear Dust: Blow out dust from driver heat sinks and cooling fins using low-pressure air.
Inspect Cords: Examine cords for fraying, cracks, or loose connections.
Check Fixtures: Check hanging cables and ratchets to make sure fixtures are secure.

Power On: Power on fixtures to check for flickering, dimming, or dead diodes.
Test Controllers: Test controllers and automatic timers to confirm correct daily schedules.
Measure Light Levels: Measure light levels with a PAR or lux meter to verify proper intensity.