Greenhouse Heating: What to Plan Before Cold Weather

Heating a greenhouse is not just a matter of choosing a heater. The structure, covering, air leaks, local climate, crop temperature needs and ventilation all influence how much heat is required and how safely it can be supplied.

Understand heat loss first

Before purchasing equipment, inspect doors, vents, panel joints and other openings. Gaps can allow warm air to escape and cold air to enter. Some greenhouse structures are not designed for insulation retrofits, so check the manufacturer’s guidance before adding materials or modifying the frame.

Match the heater to the space

Estimate the greenhouse volume and the temperature range your plants need. Heater capacity should be selected using local design temperatures, covering characteristics and professional guidance where necessary. A small hobby greenhouse and a large high tunnel have very different heating demands.

Safety comes first

Use only heating equipment approved for the intended location and follow all clearance, ventilation, electrical and fuel instructions. Do not use an indoor heater in a greenhouse unless its manufacturer explicitly approves that environment. Combustion appliances require careful attention to exhaust and carbon monoxide risk.

Protect plants during outages

• Monitor minimum overnight temperatures
• Keep sensitive plants away from cold glazing and drafts
• Consider an appropriate temperature alarm
• Have a plan for power interruptions
• Keep vents and fans functional so heating does not create humidity problems

The University of Florida IFAS greenhouse heating checklist explains how climate, structure and operation influence heating requirements. Penn State Extension also outlines greenhouse energy-efficiency measures.

Select a structure with a realistic plan

Before choosing a kit, check its intended climate, panel system, ventilation and installation requirements. Browse the greenhouse selection at Armley Bigdiscount and the greenhouse buying guide.