When growing vegetables in raised garden beds using the Square Foot Gardening method, your beds will need to be sectioned off into one-foot sections called planting squares.
A double skinned wall provides an air pocket of insulation that minimizes the temperature fluctuations and drying out of the soil in the garden bed. Sometimes raised bed gardens are covered with clear plastic to protect the crops from wind and strong rains.
This type of planting will discourage insects and specific vegetable pathogens that can stay in the soil over winter and planting that same crop in that bed will infect the crop.
Because these beds are sitting above the ground it permits the air to circulate around the containers and allows the sun to warm them up quicker. This will allot for earlier planting and quicker germination especially in the colder climate areas.