Garden / June 13, 2018 / Oriane
A raised bed is ideally 18 - 24 inches deep, but if you are building your raised beds on top of existing earth you wilI have some leeway here. I have successfully gardened in boxes built over earth with only one foot of soil depth. You can find both detailed instructions for building a raised beds and multiple choices for buying raised beds here.
Keyhole gardens are designed to maximize space by eliminating the need for walkways as found in traditional row gardening or with raised beds. The design is also intended to be draught-resistant and deliver nutrients via compost throughout the entire growing season. Keyhole gardens are a raised style bed that take the rough shape of a circle with a keyhole shaped path allowing access to the entire garden. In the center of the circle is a vertical tunnel that houses many layers of compost. As the compost breaks down it delivers nutrients and moisture directly to the bed. Certainly an efficient way to grow, keyhole gardens can be constructed with many different materials as a quick Google search of the term will confirm. If you have space for a circle roughly 8 - 10 feet in diameter you can use whatever appropriate materials that are easily accessible corrugated siding, cedar posts, landscaping rock, bricks or any combination thereof. We have a page dedicated to keyhole gardens for more details.