Greenhouses are structures designed for the protection of frail or out-of-season plants against extreme heat or cold. It is generally a plastic or glass building with a frame of galvanized steel, aluminum, PVC pipe, or redwood, cedar, or cypress wood. Greenhouses are used for the production of diverse flowers, vegetables, and any other plants that require particular temperature conditions. It is heated partly by the sun and partly by a heating system that can be modified for the plant. There are many greenhouse designs that range from the build-it-yourself starting greenhouse hobbyist to greenhouses used for mass production.
One greenhouse design that is often used is a lean-to. A lean-to greenhouse is a greenhouse that is divided along the top of the roof, or ridge line and is basically added on to the side of a house or other building structure. Lean-tos are practical where space is limited. The edge of a lean-to is attached to a structure using one side of a entrance, if possible. Some advantages to lean-tos are that they are close to obtainable heat, running water, and electricity.
Another greenhouse design is a window-mounted greenhouse. This greenhouse can be added on either the east or south side of a building or other structure. This glass area gives space for suitably cultivating a few plants cost efficiently. The special window extends about a foot or so away from the building and can contain two or three shelves to be put inside.
One of the more common greenhouse structures is a freestanding greenhouse. These are the greenhouses that are used commonly for mass production and those with lawn space. Freestanding greenhouses are separate structures and can be set apart from other buildings in order to get more sun and can be made as small or large as preferred. A separate heating system is needed, and electricity and water must be installed.