Greenhouses are used to create artificial growing environments for various types of vegetation. The extension of the growing season and control over temperature and humidity are the primary reasons for greenhouse use. Colder climates are where greenhouses are most often used during winter months. During these months temperature fluctuations can be extreme beyond the parameters of the vegetation's growing abilities. Because of this fact, greenhouse temperatures must be controlled during the winter.
Design the greenhouse with temperature in mind. Use the growing needs of the plants to determine the appropriate temperature requirements for winter. Frost-free greenhouses are the most common, keeping temperatures a minimum of 41 degrees. Use either tropical or temperate designs when working with plants needing high humidity or water plants such as violets; these greenhouses maintain a minimum temperature near 60 degrees.
Research the various heating methods available for temperature maintenance during winter. Electric heaters are the cleanest in terms of pollution, according to the West Virginia University Extension Service. Natural heating methods include solar and geothermal to maintain a more consistent temperature range. Heat sinks, such as barrels filled with water or stacked tires filled with dirt, can aid in temperature fluctuations. You can eliminate the need for walls by digging a pit greenhouse, where the ground is used to control heat.
Determining the proper location for a greenhouse is as important as the design and materials used to maintain consistent temperatures in winter. Observations of where the shade falls in both summer and winter should be made before construction. The West Virginia University Extension Service recommends locating the greenhouse along the southern or southeastern side of buildings or shade trees. Morning sunlight along the eastern side of the greenhouse allows for food production to start early and aids in maximum growth.
The West Virginia University Extension Service suggests using deciduous trees for effective shading during late afternoon. Use oak or maple to provide cover over the greenhouse from the intense sun and heat during late afternoon hours. Choose deciduous trees over evergreens because the former allows for maximum exposure during winter after leaves drop in autumn.
Maintaining consistent temperatures with greenhouse settings is crucial to the survival of plants within the structure. Install vents and thermostats to help maintain consistent temperatures. Seal areas where joints, seams and entrances are to avoid heat escaping. Plants that exist in similar temperature ranges should be grouped together since greenhouses are open spaces making temperature zones difficult to establish.