here is some more information on raised bed gardening:
Raised beds are versatile, easy to use, and have many advantages over traditional gardening. For example, a raised bed allows you to easily control your soil mixtures so that you always have the proper soil for your plants. As you can customize the soil mixtures in your raised beds, you can greatly improve soil drainage for your plants. Many gardeners build raised beds just for this reason. Raising your garden bed even eight inches above the existing ground level can greatly improve drainage.
While one of the most obvious benefits to gardening with raised beds is their adjustable height, raised beds also have numerous other benefits. For example, because raised beds are designed so that you dont have to actually step into your raised beds for maintenance, you can produce larger quantities of fruits in vegetables in the same amount space that youd use in a traditional garden plot.
Garden maintenance is also easy with raised beds. You can quickly and easily remove weeds and control pests in your raised beds. If you use black plastic mulch for weed control, you will use significantly less plastic for your raised beds that in a traditional garden. Moreover, rodents and other pests that like to eat your veggies in a regular garden bed will have difficulty reaching plants in raised beds. Crop rotation is also relatively painless in raised beds, which can help prevent problems with diseases that can form in the soil over time.
Watering is also easy and more efficient, as you irrigate only where plants are growing and not the walking spaces between your garden rows. Additionally, you can grow your plants closer together, which helps to shade the soil and reduces evaporation.
You can also quickly change soil and plants in your raised beds. For example, using a raised bed makes it very easy to plant annuals in the summer and replace them with bulbs later in the growing season.
If you grow vegetables or fruits, raised beds can greatly increase the growing season. Soil actually heats up quicker in raised beds and the addition of a removable plastic frame transforms your raised bed into an instant cold frame.
Raised beds can also make gardening more creative, as you can use many different kinds of materials to build you beds including beautiful hardwoods, bricks, stones, and recycled materials such as railroad ties.