Raising makes them higher and a little easier to reach. How high is a “raised” bed? It could be much higher than ground level to accommodate a handicapped gardener, or merely a gardener with a bad back. It can be made as high and as wide as you need. You can garden in otherwise impossible spots! With a raised bed, you have the opportunity to literally make the garden and load it with really great soil in the right spot.
Raised beds also enable you to easily alter heavy clay or rocky or thin topsoil, because you can simply add new, higher-quality soil on top of the problem. Another advantage is that raised beds don’t get stepped on so soil doesn’t get compacted!
When creating new raised beds, take soil from what will be your pathways and use it to build your beds. If necessary, bring in additional topsoil to build the depth of your beds. In either case, the planting area will be higher and deeper, which is especially beneficial to root crops.
Here are several easy ways to make a raised bed:
Make a frame using pine, which will last about four to five years and is the cheapest wood to use. Cedar is more expensive, but will last for more than 10 years. Corner brackets into which the standard lumber fits are nothing but pre-fab metal corners into which you slip your standard 2-by-4 piece of lumber — simpler than nailing. Although slightly more expensive, the corners are reusable and produce a raised bed in minutes rather than hours.
Logs will also work, but beware of railroad ties as the older ones are treated with creosote, and most of the newer ones are chemically treated, as well. Don’t use pretreated lumber! It is toxic to edible crops, and splinters are dangerous.