There are several reasons why it is a good idea to use raised beds for growing vegetables. Even if the bed is only a few inches higher than the surrounding ground, you will have the benefit of a better soil that will produce a larger crop. Clearly the raised bed really comes into its own when it is high enough to allow you to tend the plants without having to bend down. I found this article in the Homes and Garden blog which tells you all you need to know about starting a raised bed garden.

Raised bed gardening is an excellent garden plan for people with poor soil, people who have trouble bending to reach gardens on the ground or people who want to get an increased yield in their current garden. Built above the existing soil, a raised bed garden can give you twice as much produce as you previously harvested with traditional planting methods.
Raised bed gardens are larger versions of container gardens. Built above the existing soil, they can be placed directly on the ground or built up on platforms or legs, to reach whatever is your desired height. After the container is built, the garden is filled with soil and intensively planted.
Your garden plan depends on what plants you want to grow. Decide how many plants you need of each variety and plan the size accordingly. Raised beds are planted in an intensive square pattern, so more can be grown in a smaller area, but don’t underestimate the size of your planters. It is much less easy to add on to a raised bed garden than a traditional one, so be generous in your plans.

Check out the rest of the article at Homes and Gardens
Image source Ofer El-Hashahar