Gardening Help FAQs

Here are answers to some of the most common questions we receive about garden plants. You will find concise information on general gardening techniques as well as plant selection and care. For detailed information on specific plant pests and problems refer to our Common Garden Pests and Problems page.

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Horticulture Questions and Answers

How do I create a raised bed garden?

ADVANTAGES OF RAISED-BEDS

Maintenance. Raised-beds reduce bending and stooping required for maintenance. In addition, raised-beds are tended from the sides, eliminating the need for paths. This allows plants to be grown closer together reducing weed growth and competition.

Improved Drainage. Raised-beds are especially beneficial to gardeners with poorly drained soils. Raised-beds soils drain water away from plant root systems and promote better air exchange.

Expanded Growing Season. Because raised-beds are above the ground, they warm earlier in spring than in-ground beds. This allows for earlier planting and increased yields.

Better use of Space. Raised-beds allow plants to be grown in areas where conventional beds are not feasible. Such areas include rooftops, concrete or patios, and hillsides that can be terraced with raised beds.

RAISED-BED MATERIALS

A raised-bed may be made from a variety of materials including landscape timbers, railroad ties, concrete blocks, bricks, and stones. While some recommend that pressure-treated lumber should not be used for raised-beds, it has been shown this type of material does not affect plant growth. There is still debate, however, regarding the safety of fruits and vegetables grown in close proximity to pressure-treated wood. When in doubt, use untreated wood, or line the wood with heavy plastic to eliminate soil contact with the treated lumber.

Railroad ties are commonly used for raised-beds but can be problematic as they can damage plants and be difficult to dispose of later on. There are better alternatives.

Redwood and cedar are both attractive and practical for raised-beds because they are naturally rot resistant. Boards or lumber made from recycled plastics are also available. Cinder blocks are another option for quick, inexpensive, and easy construction.

Plastic lumber is a very good choice as it is rot-resistant and can make use of a recycled product, plastic.

CONSTRUCTING A RAISED-BED

The length of a raised-bed is not critical, although it is recommended that extremely long beds (greater than 10 feet) be divided into several shorter ones. The depth of the bed is also variable, but most flowers and vegetables require between 8 to 12 inches of soil for healthy root growth. If the soil below the bed is tilled and prepared, drainage is improved and roots may grow deeper than the bed itself. Bed width is a very important consideration. If the bed is to be maintained from one side only, the width should be no more than 2 1/2 feet to retain a reasonable reaching distance. For a bed with access on both sides, the width should not exceed five feet.

Stakes can be used to support the walls and should be twice the height of the bed. Half of the length of the stake should be driven into the ground, while the other half serves as support for the wall. Railroad ties and landscape timbers can be held in place with concrete reinforcing bars spaced every four feet. Decay-resistant or treated stakes should be used to support wooden walls. Mortar is required for stone walls greater than two feet tall.

SOIL PREPARATION

Before building your raised-bed, it is beneficial to work the underlying soil to encourage good drainage. This can be done by rototilling or hand digging. This will encourage good root growth for those plants that root deeply. The raised-bed itself should be filled with good quality loamy topsoil. Amendments such as compost and aged manure will help improve the soil’s tilth and fertility. A soil test should be done prior to planting.

MAINTAINING THE RAISED-BED

The maintenance of a raised-bed is slightly different from a conventional in-ground bed. Because there is improved drainage in a raised-bed, the soil will dry out quicker. In addition, raised bed soils will be warmer in spring and promote early seedling growth. Likewise they will be hotter in summer and tend to dry out. To avoid potential problems, mulch the plants with organic matter such as leaf mold or peat moss. This will both decrease moisture loss as well as keep the soil cooler. This organic material will also improve the soil quality as it decomposes. Raised beds should be fertilized in the same manner as conventional in-ground beds.

Information for this was obtained in part from the University of Missouri-Columbia Extension’s MU Guide for “Raised-Bed Gardening” available in the Kemper Center.