North Carolinians are blessed with great gardening weather, but our soil leaves something to be desired. One common method of correcting soil problems is to use raised beds for vegetables, herbs, and small fruits. Winter is the perfect time to lay the groundwork for a raised-bed garden.
Raised beds are popular for many reasons. Research indicates that a well-maintained garden can produce approximately double the conventional yield from planting in rows. This can be attributed, in part, to reduced soil compaction. Water, air, and roots all have difficulty moving through soil compressed by tillers and human feet. Gardeners can avoid the problem completely by creating beds narrow enough to work from the sides.
Raised beds allow gardeners to concentrate on amending soil in small spaces instead of tackling huge areas. A raised bed, should be wide enough to reach across, but no wider than four feet. Bed length can be whatever suits the needs of the gardener. Bed depth is normally 8 to 12 inches if you choose to enclose or frame the bed. If it’s not framed, the bed should be about six inches deep with rounded edges to help prevent erosion.
Raised beds are perfect for seniors with physical challenges due to back and leg problems. If you find it difficult to bend over, try a raised bed constructed of treated wood or composite board at a comfortable height. Raised beds also make gardening accessible to people in wheelchairs. Benches may be built around a raised bed to allow gardeners to sit and work the soil. Supports for poles, trellises, and cages can be mounted to the raised-bed frame to ensure easy installation and removal.
Pest control becomes less difficult in raised beds. If burrowing rodents are abundant, line the bottom of the bed with poultry wire or hardware cloth. To discourage rabbits, place a low, wire fence around their favorite foods. Plastic mulch is an economical way to control weeds, as a roll of plastic mulch can span the width of the bed. Raised beds create a reduction of space for weeds to grow, since the plants within the bed are very close together. Raised beds also allow for water conservation with the use of soaker hoses and drip-irrigation systems.
Soil preparation is the key to successful raised-bed gardening. There is no substitute for deep, fertile soil that is high in organic matter. Humus-rich soil holds extra nutrients and moisture. If the garden soil you have is not deep, double digging the beds will improve the soil. Remove the top 6 to 9 inches of soil from the bed. Insert a spade or spading fork into the next six inches of soil to break up compacted layers. Mix the topsoil that was removed with a generous amount of compost or manure, then return the mixture to the bed. It should be fluffy and slightly raised. Continue this action every eight inches along the bed.
The Environmental Protection Agency offers detailed information about different types of wood treatments. Borated treatments or DOT are among a number of preservative alternatives for wood handlers. Home building supply companies sell treated wood suitable for home use. However, some gardeners prefer to use untreated, decay resistant lumber from a sawmill. These should last up to 5 years when placed in contact with the soil. Keep in mind that cement blocks can raise the soil pH over time. Editor’s note: Toby will address this topic in detail in a future article.
Landscape contractors can help locate custom soil mixes for larger projects. Bagged potting soil containing pine bark fines gives excellent results for both container gardens and raised beds. Start planning or building your raised beds now to enjoy this planting season. There is no better sign of success as a gardener than eating fresh vegetables from your own garden.