If you intend on buying a greenhouse this year the first thing you must consider is the location. The location you choose will determine the success of the crops you grow as well as the durability and longevity of the structure. Also the area you have available will also determine the size and type of house you can get.
With that in mind the first thing worth mentioning is that you should always go for the largest that you can afford and fit into the space you’ve got. There is no doubt that within a half a growing season you will have filled your greenhouse and you’ll soon find yourself wanting more space. Because they can grow such a range of crops and ornamental plants it will become a though decision when it comes to choosing what to grow indoors and what to leave out in the cold.
With regard to positioning your greenhouse most people like to keep there’s inline with an existing fence, path, house or site boundary to make it fit in better. However polytunnels should be orientated along either a North- South axis or an East – West axis. This means that the front end should face due North and the back end should face due South (North – South axis) alternatively if the front end should face due East and the back end should face due West (East – West axis)
With a North – South orientation both sides of the greenhouse or polytunnel will receive equal amounts of light. With this in mind you can plan your layout and position plants with that in mind. With an East – West orientation one side of your polytunnel will be sunnier (south facing) and the other side (north facing) will be shadier. Therefore plants that benefit from shade such as tropical plants, many vegetables and for ornamental garden plants that are getting a boost before begin moved out into the garden. The sunnier side can be reserved for tomatoes, cucumbers and growing fruits.
Lastly; the greenhouse should be positioned in the brightest and sunniest location. Therefore avoid positioning on the north side of houses, sheds or walls. The greenhouse should receive at least 10 hours of sunlight in the summer. Positioning where the structure can receive the most morning sun is also beneficial. Plants like to receive sun early in the morning to allow for photosynthesis during the day. To receive the morning sun place structure to the West side of your garden so it looks towards the East. Remember that the sun is lower in the winter months than it is the summer, therefore longer shadows will be cast in the winter months meaning greater shading caused be surrounding buildings and trees. Positioning in a location that is open but sheltered from strong winds that can cause damage to the structure and glass panels over time. Therefore the best location for a greenhouse will probably be around 4 metres to the west and 1 metre to the north of an existing building, fencing or hedgerow, away from footballs and other flying objects, yet close enough to the home, a water supply and possibly electricity.