Choosing a greenhouse structure – part 1
Choosing a greenhouse structure isn’t easy. The choice of greenhouses available to buy is vast and can be quite daunting. There is a bewildering selection of sizes and designs, plus a choice of materials such as glass or polycarbonate and wood or metal. These choices affect how much maintenance you will need to do and how long your greenhouse may last before it needs replacing.
To help you make your choice it is probably best to identify your budget, your actual available garden space and what growing capacity you are looking for. There is likely to be a trade-off between these three factors but at least you will have a rough guide as to what type of greenhouse you are looking for.
Getting your garden ready for your greenhouse.
Before choosing your new greenhouse you need to survey your garden. Do this before you buy your greenhouse as your findings may influence what type and size you want to buy.
Best position and aspect
You need to place your new greenhouse in an area of the garden that catches most sunshine, that can be easily levelled to provide good foundations and that has convenient access. If you are lucky enough to have a very large garden have a look around and decide carefully which area is best. If your garden is more compact your options may be limited but it still worth checking.
It is also recommended that the greenhouse should be positioned so that the ridge-line of the roof lies east to west to ensure that the longest side of the greenhouse will be fully exposed to the sun from the south. This is good advice for a large rectangular greenhouse say 8′x20′ as you want the 20’ side to catch as much direct sunlight as possible. But, the most popular sizes of greenhouse are 6′x 8′ and 8′x10′ which are virtually square so an east to west orientation makes little difference.
If possible with a small or medium sized greenhouse try to make sure that one side is in a south or southwest facing aspect for best exposure to sunlight. But, don’t worry if this isn’t possible because at between 7′ and 8′ tall your greenhouse roof will get direct sunlight which should be sufficient to warm-up your greenhouse. Plus too much sunlight can scorch your plants and the first thing many gardeners do is to shade their new greenhouse with green netting!
If you want to reduce the amount of work you need to do before installing your greenhouse choose a level area of your garden. If there is no level are in your garden you need to create one and then lay flag stones on top. The flagstones should cover an area bigger than your greenhouse, ideally there should be at least 6 inches of flagstone protruding all around the greenhouse base. You should then securely bolt the base of your greenhouse to the flagstones before erecting the frame.
Most standard greenhouses come with an aluminium base but you can also get galvanised metal bases with superior fixings. If your budget allows it is worth looking out for this option.