We have six different sizes of Growing Dome, ranging from 15 foot diameter all the way up to 42 foot. To get an idea of the space you will need, put a peg in the ground and draw a circle the length of the radius of the dome size you are thinking of. We recommend adding 3′ to the diameter you plan on building to ensure that you have enough space to maintain the dome. This will give you 1.5′ of space around the perimeter. For example, measure a radius of 18′ if you plan on building the 15′ Growing Dome.