The plants are somewhat isolated, and therefore more protected from insects, snails, and slugs. There will be much less stooping, bending and straining in every aspect of your gardening. Raised planting beds can be designed so that they are convertible to a cold frame in the spring, allowing you to get a jump on all the other gardeners in the neighborhood. Mount permanent supports for framing poles directly to the frame of the bed. If this planting bed is for a vegetable garden, remember to rotate your crops from year to year.
Different veggies consume different minerals from the soil.
By rotating your crops, you will ensure a longer useable life for the soil. A raised planting bed is exactly what the name implies. The traditional concept of a raised bed is that of a permanent structure built to house a small garden. The bed does not however, have to be contained in this manner. If it fits your needs, you can have a truckload of soil dumped almost anywhere.