Greenhouses types can be split into two main categories: conventional greenhouses and specialist greenhouses. Conventional greenhouses include: traditional span, Dutch light, three-quarter span, lean-to and mansard or curvilinear greenhouses. Specialist greenhouses include: Dome-shaped, polygonal, alpine house, conservation, mini and polytunnel greenhouses.
In the next lines we will try to describe every of those types and see what are their main qualities to help you choose the most suitable greenhouse for your garden.
This type of greenhouse is practical in terms of growing space and headroom by its vertical sides and even span roof. It provides the best use of space for the least cost for raising seedlings and growing border crops. Its lower part stop the heat lost over the winter.
This type of greenhouse is designed in order to allow in maximum light through the sloping sides. It is suitable to grow border crops, preferably low-growing ones. The panes of glass on the roof overlap slightly to keep out rain but also to increase the rigidity of the structure.
This type of greenhouse is positioned with one of its sides against a wall, preferably beside a sunny wall because the light is a little more restricted than in a free-standing greenhouse, but this also mean that it will need some extra shading in the summer. If you will choose a house wall to position your greenhouse you will also benefit from extra warmth and insulation from this.
You can use this type of greenhouse in a garden with insufficient space for a free-standing structure. Like the three-quarter span, this type of greenhouse will benefit from the warmth and insulation of the house wall. Many of those greenhouses are similar in appearance to conservatories and may be used as garden rooms. In this type of greenhouse you can install electricity, gas or water supply more easier and cheaper than in a greenhouse that is placed at some distance from the house.
Mansard or curvilinear
This greenhouse has slanting sides and roof panels designed to allow in maximum light available so a best place for this type of greenhouse is an open site with no shade from the surrounding trees or buildings. This greenhouse is suitable for plants that need maximum light over the winter.
This type of greenhouse is offering an elegant design that is mostly useful in exposed positions. It is stable and offers less wind resistance than traditional greenhouses. It allows maximum light transmission because of its multi-angled glass panels. It might offer limited headroom around the edge.
For a focal point in the garden or for gardens where appearance is important those greenhouses are the most used. Any octagonal or polygonal greenhouse is a good choice, but they may be more expensive than traditional greenhouses of similar sizes.
Traditionally those greenhouses have timber-frame with louvre vents all along the sides. This help for a most effective ventilation. Usually, this type of greenhouses are not heated and they are not closed unless the winter is too cold, so the insulation is not needed. They are used mostly for plants that just need some protection from dampness and rain and require a bright and well-ventilated place.
This type of greenhouse is designed to save as much energy as possible using special features. The roof panels are angled to permit optimum light penetration. Mirrored surfaces are also used to reflect light within the greenhouse itself. With all those special features, this type of greenhouse is usually more expensive than others of the same size.
For a limited space in your garden, or if you only have a small number of plants to grow, this useful, low-cost greenhouse is available in different sizes and also as free-standing or wheeled versions. Made from aluminum frame and covered with plastic or glass, this greenhouse is best to be placed face SE or SW in order to get the maximum light penetration. Access may be a problem as all the work has to be done from the outside. Venting and shading in the summer are essential.
For a low-cost protection, for the vegetable plot for example, a plastic polytunnel greenhouse is the choice. It covers a large area, is covered with heavy-duty transparent plastic sheets and offers protection from cold and wind, is easy to move where needed, so is the perfect choice for your crops, either you choose to plant them directly into the soil, in pots or in growing bags. Ventilation may be a problem and the sheets may need to be replaced every few years as they gradually become opaque.