The depth of the bed can vary, but six inches of soil is a minimum. Plants need at least a 6–12-inch rooting zone, so 12 inches is ideal. Before you establish the bed, break up and loosen the soil underneath with a garden fork so that it’s not compacted. Go about 6 to 8 inches deep.
For the experienced gardener or the novice, raised garden beds take the hassle out of horticulture. Here are tips on planning, building, protecting and irrigating raised bed gardens.
When first setting up a raised bed, gardeners should ‘double-dig’ the soil beneath the raised bed. This only needs to be done once and is much easier if done before the raised bed is assembled in place. Double-digging refers to two shovel blade lengths, or approximately 24” in depth.
How deep (or tall) a raised bed should be depends on the rooting depth requirements of the plants you wish to grow, and whether the ground below the planter is made of healthy soil. Deep rooted plants such as tomatoes, zucchini, corn, and perennial fruits and vegetables, do best in planters at least 22 inches tall, or shorter if the ground below is usable.
What size will it be? Raised beds are generally three to four feet wide by about six to eight feet …
How to Make a Raised Bed Garden. However, to ensure that your plant’s roots have plenty of room to grow, it is a good idea to dig out the existing sod and loosen the soil with a shovel or garden fork to a depth of eight to twelve inches.