Building a raised garden bed out of new lumber or raised garden kits can be a very expensive project. According to several university agricultural extensions, including the University of Missouri, making a raised garden doesn't require spending a lot of money. With prior planning and a little extra work, you can build a raised garden bed without any expense.
Stake out an area where the raised beds will be located. Raised garden beds should be no wider than 4 feet wide to allow for easy access to the plants. The length of the bed can be up to any length that is convenient or logical for the gardener and the site.
For a no-cost garden, clear the soil of all debris using a shovel and garden rake, then use a tiller to turn the soil to approximately 12 inches deep. If you are purchasing soil, the ground can be prepared by covering it with thick sheets of newspaper to block out weeds, pouring the soil on top of the newspaper to the desired thickness and spreading out with a rake.
Spread a 2- to 3-inch layer of composted material over the garden site and mix it into the soil using a shovel or garden rake.
Level out the garden soil, using a garden rake to flatten the top of the bed and taper the sides of the mound on an angle. The bed can be used as it is now for one season. Avoid walking on the soil to help keep it from being compressed down.
Line the border of the bed, if desired, with medium to large rocks from your property, build a frame from used boards or tree limbs or use any other appropriate materials that have been recycled from other projects. It is not necessary to use any of these materials, but many gardeners prefer to distinctly define the boundaries of their garden beds, and any sturdy material will work.