There are several types and many sizes of greenhouse in use today.
The glass to ground with a span roof has high eaves and vertical sides.
It is best suited for growing carnations, tomatoes and many other plants requiring plenty of light.
The maximum amount of light is admitted warming the ground thus conserving heat.
Brick based spanned roof greenhouses were mainly built in Victorian times to cultivate pot plants and are entirely unsuitable for tomatoes and carnations etc.
They are still available today with a timber base.
They usually have some form of staging, the base of which can be used for storage only as nothing will grow here.
The Dutch type span roof has sloping sides which slope outwards.
It is usually glazed to the ground and therefore suitable for plant which must have plenty of light.
There is one disadvantage with this design being unable to accommodate tall plants near the glass sides.
The lean-to greenhouse is only recommended now where there is no suitable site for a span roof type.
For maximum protection from the wind this type is best erected facing south.
It has an advantage of gaining some heat radiated from the house wall.
There are a large number of lean-to houses, some of these are glass to ground and others have timber bases.
The Dutch type lean-to can give a good width and can be fixed against fairly low walls.
The three quarter span greenhouse is just a modified lean-to which allows some northern light to enter.
Fruit trees such as peaches can be grown or ornamental climbers as these can be trained against the high wall.
To provide the best of both worlds a dual purpose greenhouse can be obtained.
These houses are glazed to the ground on one side only, the other side being boarded up to provide winter storage foe fuchsias, dahlia tubers and other plants.
The key element to a successful greenhouse is to admit the maximum amount of natural light as possible.