Extending the growing season in cold winter climates is an attractive option for avid gardeners, and many have constructed greenhouses next to backyard gardens. Whether the goal is to get a jump start on a summer garden, to house delicate flowers, or to grow citrus fruits in cold climates, most greenhouses can be constructed by the novice builder. Costs run from the budget friendly use of salvaged materials to high priced greenhouse kits purchased from deluxe gardening stores.
The first step in building a greenhouse is site selection. The greenhouse should be placed on a level, solid piece of ground with southern exposure. It's best if the top ridge of the greenhouse runs from east to west as this angle allows for the most sun exposure in winter months. However, grow lights can be installed if greenhouse placement fails to provide adequate sunlight exposure.
The next step is to build the foundation and there are several requirements to adhere to. The foundation must be anchored to the ground, allow for water drainage, and steps should be taken to inhibit weed and grass growth in the greenhouse floor. Foundations can be made quite easily and cheaply from wood, but cement slabs are also frequently used.
Framing is done next. Different styles and materials can be used for framing, but the typical backyard greenhouse is constructed of either wood or PVC plumbing pipe, though kits will often provide frames made of aluminum. Greenhouse plans can be found anywhere on the internet, but the basic frame is a simple rectangular structure, with walls made of beams set at equidistant positions along the base. A roof is added, then the covering is attached.
Greenhouse coverings are commonly made of polycarbonate or polythene materials. Both of these offer a range of options in durability and resistance to chemicals and UV rays. Selection is highly dependent on area and purpose of greenhouse and can accommodate most budgets. Instructions for installation of coverings varies depending on the materials used, so individual instructions should always be consulted.
After construction, modifications can be made to alter the temperature to suit the plants housed within. Doors and windows can be added to allow for better ventilation, and small heat lamps or heaters can be placed inside on very cold days. Much care should be given to the placement and use of any electrical devices within the greenhouse as smaller houses will easily overheat.