Making the proper foundation for your greenhouse

Most greenhouses must have a plane and firm foundation. However, how much work you need to do before you assemble or build your greenhouse depends on the type of greenhouse you want. If you go for a simple polytunnel greenhouse, you can more or less put it anywhere. Place it directly on the ground if the ground is nicely even and plane. Many of the greenhouses with a frame in aluminium or galvanised steel require a little more. If you place the frame directly on the grass or soil, it must be level – otherwise, you will have trouble with the door and more nor working correctly. If you use a base for the greenhouse, you adjust that to make it level and then place the rest of the greenhouse on top of the base.

If you can get a base for your greenhouse, we always recommend that you use that. It will fit, and you can make sure that your greenhouse is level – and it will be a little taller – not so much, but the base will lift the entire structure app. 10 cm. If the base is not enclosed when you order the greenhouse, it is often possible to order the base separately.

Another solution is to make a firmer foundation in flagstones or wood. It takes a bit of work but often, it will be worth the effort as you get a nice deck inside and maybe around the greenhouse. If you are going to use your greenhouse as an orangery or a gazebo, you can place it on a wooden deck, which will work as an elegant flooring at the same time. Do you want to have large containers with soil for plants inside the greenhouse, be sure to make the wooden deck strong enough! With flagstones, the weight will be no problem, and you can easily remove one or more flagstones if you want to plant directly in the soil underneath.  

You can also go all the way and cast a foundation in cement. Here you may consider how deep the foundation should be concerning creating a frost-free floor in the greenhouse – in general, we are talking about 90 cm, but you need to check that with an artisan as it can vary depending on the soil and more.

Before you start making a foundation, you need to find the right spot in the garden. This guide can help you find the right place following the sun and much more. The guide can help you find the best location for your greenhouse - depending on the type of greenhouse you want, whether you use it only in the summer, and what you want to plant in it. When you have decided to have a greenhouse, normally, one has an idea of how it should be – but it is still a good idea to search for the best solution.