There are many advantages to having raised beds in your garden. The soil in a raised bed is less compact, drains well and heats up quicker in warm weather. For the gardener, it is easier to work on plants in a raised bed as there is less bending and kneeling. Raised beds can be constructed out of a number of materials including, brick, timber and old railway sleepers. If you are using timber or wood and it has been treated with wood preservative, then you will need to line your bed with polythene sheeting to prevent any chemicals from leeching into the soil.
Raised beds are ideal for growing vegetables. Parsnips and carrots grow especially well in the deep well-draining soil. Cover young plants and seedlings with plastic sheeting during late Spring frosts. If you have 3 or 4 (or more) raised beds dedicated to growing vegetables, then ideally you would rotate the crops grown in them every year. This prevents the build-up of specific diseases and pests which are particular to a specific crop. If you do manage to rotate the crops grown in your raised beds then this will also help to maintain nutrients in the soil.