Posted: 01/06/2016 at 13:59
Janet, the beauty of a raised bed is its versatility you can make them as high wide as you wish and you do not need sleepers. When my wife took ill we built some raised boxes around the seating area with scented flowers in them, They were tannalised board on stout corner timbers lined with old compost bags they lasted ten years until I took them out still looking good for another ten years.
The idea of raising beds for vegetable is to make no dig areas so six inches high will do, I did not line the bottom just dug it over first then added good compost. Plants can be closer together and as one crop is over rake the soil add more compost and sow another crop. Raised beds as with all gardening is a mix of experience and common sense, sow enough to cover any failures and sow little and often, no waste or over abundance.