Raised planter gardens have many benefits over traditional garden spaces; the main benefit being that you can adjust them to your needs. Planter beds use less space, and give you greater control over the soil quality. The ability to work all the way around a planter bed prevents soil compaction as well.
Plan planter beds in an area where they receive full sunlight. If full sunlight is not available, choose an area with morning sun. If only a shady site is available, says Texas A&M University, grow cool-season vegetables such as lettuce, cabbage or broccoli.
The size of the raised planter garden determines how it can be worked. Limit the width of the planter so you can work from both sides. Raised planter gardens that are only to be worked from one side should be limited to 2 to 3 feet in width, while those that are to be worked on both sides can be 4 to 5 feet, wide says Iowa State University Extension. Keep the height of the raised garden bed limited to 2 to 3 feet in height if the gardener is in a wheelchair. Otherwise, adjust the height so you can work the raised planter from a standing position.
Depth and Design
Raised planter beds do not have to be deep to be effective--8 to 12 inches of soil is enough in most situations, but vegetable beds require 12 to 18 inches.
The edging of the bed not only supports the soil but it determines the aesthetic appeal of the garden. Metal edging is easy to install but will likely rust over time. Wood timber is appealing, especially railroad timbers that are treated with creosote, as usually the creosote has leeched away. Treated wood may pose environmental dangers due to the chemicals used. Stone, brick or cinder blocks are the most durable, but may be expensive.
When designing a raised planer bed, determine the irrigation method ahead of time so you can integrate it when you build it. Hand watering is easy but may become tedious over time. Low-flow micro-irrigation systems are the most effective method of irrigation. Automated sprinkler systems often have to much drift and evaporation, causing water loss. When filling the raised planter bed with soil, you can install drip tubes under the soil, near the plants, with a 12 inch emitter spacing.
Soil used in raised planter gardens should be a mixture of three-fourths top soil and one-fourth organic material, such as compost. The higher the organic material, the earlier you will need to add more soil or compost to the garden to compensate for decomposition. Vegetables do best in a different soil mixture composed of one-third topsoil, one-third peat moss and one-third sand or coarse perlite for drainage.