Raised garden bed
A raised garden bed is a method of gardening where the soil is elevated higher than the access paths, contained by some material. The enclosure and the soil is referred to a the garden bed. Raised garden beds provide a more ergonomic means of gardening, allow greater control soil and water, reduce soil compaction, control erosion, and extend the growing season.
Material selection
The beds are often made of wood, rock, brick, or concrete.
Wood, such as pine, is an inexpensive garden wall but has a short life before it decomposes and needs to be replaced. Rot resistance wood, such as cedar, will extend the life of the beds but will cost more and will still eventually decompose. Pressure treated wood should be avoided, especially when growing edible produce, as the chemicals used can leach into the soil and accumulate in the plants.
Concrete masonry unit bricks are an inexpensive option, but should be avoided as they are often made with fly ash.[1]
Dimensions
For comfort and for full access, beds should not be deeper than two feet from the path. If a bed can be accessed from both sides, they are typically four feet. For large areas, efficient garden beds are rectangular with 4 foot depth (or 2 feet depending if it is against a barrier like a fence or building). The length depends on material available and the layout needs. Three feet spacing between beds allow for wheelbarrows. For smaller areas, a keyhole garden shape may be ideal.