But a raised bed does not have to be a plain wooden box.
On decent soil, beds 11 to 12 inches tall are plenty, because roots grow down into the ground below.
Lifespans depend on climate, moisture and thickness, so treat them as relative.
Cedar resists rot naturally, weathers to an attractive silver-gray, and is the traditional choice for raised beds.
Beds 24 to 30 inches tall let you plant, weed and harvest without kneeling.
Rows of identical 4-by-8-foot beds with 18- to 24-inch paths are efficient, easy to plan and simple to rotate crops between.
Bend a length of sturdy livestock panel into an arch between two beds.
Step-by-step advice, charts and free garden calculators at Garden Voila.