Raised beds are a great option for most vegetable gardeners, especially if you only have a small amount of space for a garden. A raised bed is nothing more than a box or container with soil placed on top of the ground. Raised beds typically are more productive than in-ground beds because the soil is less compacted, has better drainage, and warms and dries earlier in the spring, allowing you to start gardening earlier in the season.
Raised beds are also often easier to maintain, particularly for gardeners with limited mobility, and generally have lower perennial weed pressure. The main disadvantages of raised beds are that they tend to require more frequent irrigation and have a high initial cost of construction. The advantages, however, typically outweigh these disadvantages over the long term.
Design & Construction
Gardeners can purchase raised bed kits that require assembly, or you can build beds out of many different types of materials. Large containers such as livestock water troughs are popular right now for their industrial-chic appearance and these containers make excellent raised beds.
Most gardeners elect to build beds out of non-treated rot-resistant lumber such as cedar, oak, or locust. Bricks, rocks, and cinder blocks can also be used. Gardeners should avoid the use of used railroad ties and tires as these items have the potential for leaching toxic materials into the soil.
Proper design and sizing of a raised bed is critical so that the gardener can easily accomplish all garden tasks while outside the bed, so beds should be no more than 3 or 4 feet wide, and even more narrow if young children will be gardening in the bed. While the length of the bed is less critical, many raised beds are designed to be a maximum of 8 feet in length.
Soil in raised beds should be a minimum of 6 inches deep and 8 to 10 inches is desirable. Raised beds can be placed directly over existing sod or soil, and a barrier does not need to be placed under the raised bed.
Raised beds can also be elevated several feet off the ground to allow individuals with limited mobility or those confined to a wheelchair to enjoy the therapeutic benefits of gardening. Such beds should be designed to be a maximum of 24 inches wide to allow easy access to the entire bed.
Soil
One of the greatest benefits of gardening in raised beds is the ability to grow in lighter, less compacted soil with more pore space for air and water, so filling raised beds with native soil dug from existing in-ground growing spaces is not recommended. Ideally, raised beds should be filled with a mixture of quality garden soil and compost. Many garden centers sell bagged soil blended specifically for use in raised beds.
Location
Like any vegetable garden, raised beds should be located in areas that receive a minimum of 6 to 8 hours of direct sunlight each day. Raised beds can be an option for utilizing sloped locations if the beds are terraced during construction. Ideally, raised beds should be located close to a water source to facilitate frequent irrigation. If you build several raised beds be sure to allow for adequate space between beds to facilitate working in each bed as well as maintenance of the beds.
While a raised bed won’t solve every problem a vegetable gardener might encounter during the growing season, it will provide an opportunity to produce more vegetables in a smaller space while reducing the labor involved with routine garden maintenance chores.
Mike Hogan, hogan.1@osu.edu
Extension Educator & Associate Professor,
Agriculture & Natural Resources
2019 Faculty Council Chair
OSU Extension, Franklin County
Past President, National Association of County Agricultural Agents