News » 09.07.2025 - How to heat your greenhouse safely and effectively
To maintain healthy yields, greenhouse growers must cultivate optimal temperature and humidity levels year-round. "Even in the most idyllic climate, sustaining healthy growing conditions can require the use of strategically placed heating units", Jamie Tuinstra of Modine says. Modine is a global company with more than 100 years of experience in thermal heating, headquartered in Racine, Wisconsin (USA). "After all, the entire concept of a greenhouse is that it traps thermal heat, making it possible to maintain a fecund atmosphere in which plant life can flourish. The problem is, colder climates and wintery seasons mean that thermal heat dissipates, leaving greenhouse growers to make up the difference."
Not all greenhouse heating solutions are created equal, however. It's important for growers to know their options and to find a heating system that's not only effective, but also safe.
The importance of optimal heating
Different crops have different needs, but it's customary for greenhouses to maintain temperatures in the range of 75-85 degrees. Ambient weather can be unpredictable, with plenty of fluctuation even within a given season, but an investment in climate control ensures consistency.
"Not only do plants require temperature optimization, but they also thrive in idealized humidity—here again, climate control can be a big help, helping to manage the right moisture levels. Heating systems proactively promote flourishing plant growth, but they can also help to protect plant life from harm. For example, in colder environments, heating systems can prevent against frostbite and other forms of cold weather damage."
Effective greenhouse heating solutions
When it comes to selecting the right heating solutions, different greenhouse facilities will have different needs, dictated by factors such as local climate, the size and layout of the greenhouse and more, Jamie explains.
"To ensure consistent temperatures, placing a number of unit heaters may be the best option. Unit heaters can be strategically mounted on posts, doorframes or walls throughout the greenhouse to ensure that each section gets the heat it requires.
Fuel source will be a major point for consideration, with electric and gas-powered options both on the table. Either option can provide a consistent temperature, and even infrared units may be useful for providing targeted heat to smaller sections of the greenhouse."
To ensure efficient climate control, it's important to consider not only the heat source but also the facility's insulation. "Double-paned glass can help minimize heat transfer, as can sealing any cracks that appear along doors, windows or the line of the greenhouse roof.
Thermal mass can also be a helpful concept when considering energy-efficient greenhouse heating. Simply put, certain materials—think bricks and water barrels—absorb heat during the day and then release it during the night, promoting uniform temperatures while reducing the facility's reliance on artificial heat. This can be a smart way to curb utility bills and overall energy consumption."
Of course, there's also heat from the sun itself. The use of reflective surfaces can help capture and reflect the sun's heat, allowing the greenhouse to leverage passive solar power—thus allowing unit heaters to work just a little less hard.
Putting safety first
While dependable heating is vital for healthy greenhouse growth, there's another concern that should be top-of-mind when selecting new heating units—and that's safety. To prevent unit heaters from becoming health hazards, Jamie gives some best practices to consider.
"Don't forget about ventilation and airflow. Proper ventilation ensures that fume build-up doesn't occur, even with gas-powered units. Electric heaters don't require ventilation per se but it is important to ensure healthy air circulation, which can prevent these units from overheating. In addition, good air circulation can prevent mold and mildew growth, which can be especially problematic in a greenhouse setting."
Look for key safety features. "Today's unit heaters often come with built-in safety precautions, including automatic shutoffs that safeguard against overheating. Such features can greatly reduce the risk of greenhouse fires, so it's always smart to ask about them when shopping for a new unit heater."
Follow proper shutdown procedures. "When powering down a heating unit for the warm season, follow the recommended shutdown steps. This usually means lowering the thermostat, powering down the unit and turning off gas valves, but specifics can vary depending on the unit heating model. Always consult the manufacturer's guidelines."
Be diligent about routine maintenance. "Attending to regular unit heater maintenance, including regular visual inspections of the wiring, not only promotes equipment longevity, but can further reduce the risk of fire and other catastrophic events."
The bottom line for greenhouse growers is that consistent climate control matters—and investing in the right heaters, along with appropriate heater positioning and maintenance, can ensure both efficiency and safety.
Source: wwww.floraldaily.com
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