Controlling Greenhouse Temperatures

Good temperature control is very important to maintain a high quality crop. Heating systems commonly used in greenhouses include the following:

Steam heating systems - typically used in large greenhouses.
Hot water heating systems - typically used in smaller greenhouses.
Forced-air heaters - commonly used in commercial greenhouse ranges. Problems with the dryness of the heat occur with this type of heating.

Each of the above use oil or propane to fuel the boiler, which may cause problems with pollutants such as propylene and ethylene.

Infrared radiant heaters - The major advantage of this type of heater is that it conserves energy and has no problems with pollutants. The disadvantages associated with this heating system are:
- Cost
- It may be difficult to monitor the actual temperature received by the plant since air temperature is not a good indicator. Infrared heaters warm plants and other objects in the greenhouse but not the air temperature to the same extent.

Greenhouses need to be ventilated and cooled throughout the year. During the summer and even the winter months the air temperature in the greenhouse may become too high and inhibit plant growth. In addition to cooling, ventilation of a greenhouse provides the following:

Renews the supply of carbon dioxide needed for photosynthesis.
Circulates the air to reduce the chance of diseases.
Prevents ethylene buildup.