If you are the “do-it-yourself” type then you may want to consider buying a greenhouse kit. This will be the least expensive type of greenhouse and a great starting point for those new to gardening with a greenhouse. There is most assuredly a greenhouse kit available to suit your gardening needs. Greenhouse kits are available for portable plastic greenhouses, indoor greenhouses, large greenhouses and more.
Most kits for building a greenhouse are constructed with plastic sheeting or plastic panels also known as polycarbonate panels. The frames can be aluminum, pvc piping or wood. Greenhouse kits come in a variety of sizes and colors, so keep in mind what you want the function of the greenhouse to be. If this is your first greenhouse you may want to start with a small inexpensive one.
The main function, the size of your yard, the location you want to put the greenhouse and of course your climate should all be considered when choosing a greenhouse. Be sure and check your local building codes if you are planning on building a large one - you may need a permit.
Most greenhouses should be facing east and west so as to maximize sun exposure. Protection from northern winds should be a consideration also. Think about where in your yard throughout the year will the most sun exposure be.
Consider that if you build near very close to the house you may be able to use use the electricity and water supplies within your home to power your greenhouse.

