Greenhouse Heating and Cooling
The main goal of greenhouse gardening is to provide a controlled environment. Many people only consider how to get heat into the greenhouse but in warm months and sunny days, your greenhouse requires a source for cool air intake too.
How do I heat my greenhouse?
In a moderate climate, the best choice for keeping a greenhouse above freezing is a small electric heater.
For larger greenhouses or small greenhouses in cold climates or those requiring a hot house environment, we would recommend electric, propane or Natural gas heaters. The capacity is dictated by four things:
- the cold outside temperature at night
- your desired night time minimum temperature in winter
- the surface area square footage of the greenhouse
- what glazing you choose
We have a formula that provides the heating requirements for your greenhouse. Contact one of our greenhouse experts today to talk about your growing needs.
Tip For Orchid Growers – backup generators are common or gas heating in the event of power outages. Portable camping heaters are also used in the event of power outages.
How can I incorporate solar heating in my greenhouse?
- Black barrels filled with water are commonly used to heat a greenhouse.
- Solar panels would provide some energy in a warm climate but would not provide the amount of electricity needed to heat a greenhouse in a cold climate.
- Energy curtains are often used to retain heat generated in the day and reduce the volume of the greenhouse needed to be heated. This increases energy efficiency by heating only the space in use.
- Some greenhouse gardeners like to create different zones in their greenhouse and will use energy blankets or plastic partitions to create the temperature differences. It is important to note that we do offer greenhouses with built in partition walls as an added feature.
What about In-Floor or Radiant Heating in my greenhouse?
In-floor heating is not recommended as the only source of heat as it will cause roots to burn. The radiant heat from baseboards is ideal as forced air isn’t as natural for plants.
Is Geothermal a good idea?
Geothermal heating is a great option although it tends to be quite expensive. Many of our customers include it with a new build or another project.
How do I cool down my greenhouse?
Passive ventilation is still the most popular form of cooling as it is the most natural and gentle for your plants. This is achieved through automatic ridge vents and optional side venting. This relies on convection as the hot air will naturally rise out and cooler air can be drawn through the lower openings.
For larger greenhouses or hotter climates, a forced ventilation system may be necessary to ensure the greenhouse does not over heat. This will usually include a combination of exhaust fans and motorized intake shutters with thermostat. When choosing a forced ventilation system, plan on relying on it for most of spring, summer, and fall. You can use your passive ventilation methods with your vents. This means a less extreme temperature fluctuation and is better for your plants. Be careful with warmer winter days as you do not want a flash of cold air hitting your plants.
What about a shade system?
Diffusing harsh sunlight will also minimize heat build-up and harmful rays. Many plastic coverings act as a built in shade system. With a glass greenhouse, some form of shading will be required if there is not adequate natural shade available in your yard. Many greenhouse owners still use whitewash to diffuse the sun or ask us about our various shade cloth options.
Air circulation is important
It is more important than most people realize. Every greenhouse needs to have a circulating fan moving air at all times. Although the idea is basic, the principle is critical. Plants need fresh air for a healthy root system and a constant flow of air prevents pockets of warm or cool air staying in corners. It will regulate temperatures and increase efficiency in the greenhouse. This will also prevent mold from forming on walls or plant containers as condensation is less likely to settle especially in a structure like ours that is so well sealed for inclement weather.
Create a micro weather system for the best results!
Place your heater on the floor pointing into greenhouse closest to the door (the source of heat loss). Put a circulating fan on bench level pointing up and towards the door. This will create a circular motion of needed air for your plants and increase efficiency in the greenhouse. If you have a larger greenhouse, a few small Caframo circulating fans will be your best friend. Talk to us about your circulation and ventilation needs!