Before you buy your new greenhouse, there are a lot of decisions to make, such as what size it needs to be and where exactly you are going to put it. Think about how much space you will want or need outside the greenhouse and it is important to work out whether the building is going to be permanent or not. If you can see yourself selling your property in the future, will you want to take the greenhouse with you or will the new owner want the greenhouse?
Whatever you do, keep the greenhouse away from large trees. A falling branch will go straight through a greenhouse and when you are digging foundations you do not want to have to deal with large roots.
Getting The Greenhouse Up
The idea is to get the greenhouse up with the minimum of fuss so choose flat ground which will need a minimum of clearing. Do not put it in an area where the soil is lightly packed. The greenhouse needs to be level. If it isn’t it can warp, creating gaps between the glass and the frames and even causing the panes to fall out. You might find with a greenhouse on a tilt that you cannot fasten the door properly.
The size of the greenhouse and how long you want it to last will have a bearing on the type of base to use. Most bases are either concrete, paving slabs or wood. Railway sleepers, if you can get them, can be ideal in some situations.
Concrete, of course, involves the most work, but it is permanent and very secure. If you are planning a large greenhouse, then you will probably need concrete. The greenhouse will be bolted to the base. This makes it very secure and level. There is no chance of it being blown over in high winds. The only problem arises if you want to move the greenhouse later. You will be left with a large area of unwanted concrete, so choose wisely.
For a smaller greenhouse, paving slabs are a good choice and involve far less work than the concrete base. They can also be moved much more easily. They are better laid on a bed of gravel to improve drainage. There is always water in greenhouses, no matter how hard you try to keep them dry. Water gets in from spillages or leaky frames and even condensation. With paving slabs, the water can escape through the gaps between the slabs. The greenhouse should be staked down for stability.
The easiest option is wood, which works well for smaller greenhouses. This involves four posts, made out of wood or sometimes concrete, being driven into the ground. These will be the four corners of the greenhouse. Then beams are laid as a frame on top of the posts and the greenhouse is put on top of the frames. It should be staked down. One advantage is that the greenhouse is raised slightly off the earth which allows for ventilation underneath. Wooden posts will rot eventually but not for about 20 years and wooden foundations make it much easier to move the greenhouse.