You have just ordered a greenhouse for your new tomato plants and are already planning the drainage system, the thermometers, and even the heaters you will use. Then, it hits you – the floor on which your current greenhouse is set isn’t level.
With the upgrade to a greenhouse, you will need to create a level, secure, and durable surface so that your tomato plants don’t get blown away or sink into the ground! This may sound complicated, but don’t worry; it really isn’t.
Even if you are renting your home, you can still lay a temporary foundation to support your greenhouse, which this guide will go into, along with some of the cheaper and more common options available on the market today.
If you are going to place your greenhouse in an area with soil, then the easiest and cheapest option is a compacted soil foundation. Make sure this is level so that it doesn’t stand at a crooked or slanted angle when you put your greenhouse up.
This is also the best solution if you have a smaller greenhouse or one that is less than eight by ten feet. Do greenhouses need a foundation if they are bigger than this? Absolutely – but compacted soil is unlikely to be the best choice for heavier greenhouses and larger plants.
Slabs and Decks
This is the next stage up from compacted soil, which you will still need to build this base. Slabs and decks can be cemented in place or simply placed on the area where the greenhouse will stand. They are usually made of stone, concrete, wood, or brick.
The size of the slabs and decks you will need will depend on the size of the greenhouse and any patterns that you may want to make on the floor of the structure. These can be pricier, but overall, they prevent mold and dampness that can occur with the compacted soil option.
Yes, you read that right! The material that became a fad a few years ago for driveways is now being used as flooring for greenhouses. A great reason to use gravel on top of compacted, flat soil is that it is easy to get hold of, easier to level than slabs or decks, and allows for drainage.
In particular, if you have a greenhouse that has a sprinkler system set up to humidify your plants throughout the day, you will likely want to invest in a gravel foundation for your greenhouse.
If you want to place your greenhouse on top of a foundation of bricks, you may or may not need to check your property code – even if the foundation is temporary. Bricks usually require cement to hold them together, so to be on the safe side, check with your housing authority.
Still, bricks make an excellent foundation for greenhouses; they are attractive, retain heat, and are also light and cheap enough to get from most home supply stores without much hassle.