raised garden bed
Types of Raised Beds
The best type of beds to utilize will depend on personal taste and budget. Building a raised bed is a small job for a contractor but if you're handy, build your own. Raised beds can be built with ledges around them for sitting and seated gardeners sit sideways to work unless using a tabletop type. Tabletop beds have room for knee space, which might be easier on your lower back, but they're shallower so require more frequent watering.
Ready-made plastic, cedar, and other beds are available in large sizes in gardening catalogs and centers. A garden center can also give you resources for landscapers and other contractors. Many carry "how-to" guides for building raised beds and other projects. Be sure to see the resources at the end of this section.
The easiest types of raised beds to build are made with landscape ties or with two by four-inch wood planks. Other raised beds are made from railroad ties, flagstone, bricks and mortar, and cinder blocks. When using wood, a pressurized, chemical-free type is usually recommended, especially if you'll be growing vegetables, because chemicals can be toxic to them. If you line the inside panels with plastic, that will form a barrier from the chemicals. However, don't put plastic on the ground because it'll prevent proper drainage. Placing landscape fabric over the plastic and bottom will keep weeds out.
An ideal size for a raised bed is 4 x 8 feet or 8 x 12 feet, if you're ambitious. Bed height for wheelchair users should be between 18 and 30 inches high, depending on need and preference. A standing gardener with difficulty bending from the waist should build a taller bed  (about waist level or taller):
Filling a tall bed partway up with crushed rock will save on soil and provides good drainage. Non-disabled gardeners can build raised beds starting from about 10 inches tall, as long as there's ample room for soil and drainage.