We put in 18in raised beds last year. It's a ton of soil. Plants can get big. Kinda gotta plan by what you want and like for your own garden. Pumpkins and squash will vine out and will overtake the bed or you gotta run em out over the yard. Kale and lettuce grow like crazy, if you don't want a salad everyday day they can be tough to keep up with... I think carrots are cool since you can leave em in the ground forever and you never really know what you're gonna pull out