The greenhouse site must be level, this will help ensure an easy and straightforward assembly. Your greenhouse must be anchored securely to the ground. This is best done in one of two ways. You may pour a concrete strip foundation (to the frostline is recommended by the manufacturer) or you may purchase a foudation/base frame kit for the greenhouse. The unique foundation frame eliminates the need for concrete. It hooks to the bottom of the greenhouse and is buried in a trench that is about 5″ deep all the way around the greenhouse. This will securely anchor the Riga greenhouse. Occassionally, we have also had people pour full concrete slabs and use anchor screws with the supplied L brackets – if you do this, please account for drainage. You can also find a wealth of information to prepare for your greenhouse in the first section of our assembly manual, which can be downloaded on the product page.