MAKING RAISED BEDS

A raised bed is an excellent way to solve some of the drainage problems we have here in Cumberland County. A raised bed is simply a planting area that is higher than the surrounding soil level.

Site: The raised bed should be placed where exposure to the sun is possible for at least 6 hours daily for most vegetables and flowers. Locating it near the kitchen makes harvesting of vegetables and herbs convenient. A source of water for irrigating is important because the soil in a raised garden bed tends to dry out faster than that at ground level. Use a herbicide or pull all weeds and roots in bed area. A 4" border of bare soil around the frame will make mowing easier and will keep grass from growing into the bed.

Material: Most gardeners use green "pressure treated lumber" commonly sold at lumber yards. The wood has been treated with chromated copper arsenate (CCA) or ammoniated copper arsenate (ACA). Despite the chemicals used in treating them, these two preservatives are actually safe for the garden because of their very low tendency to leach into the soil. Research studies have shown that there is practically no chance of ingesting arsenic in vegetables grown near treated lumber. However, because of the arsenic in the wood, it is advisable to wear gloves and a dust mask when sawing the lumber.

An alternative is to use untreated lumber, although it will last a shorter time, and replace the bed frame more often.

Cinder block is another readily available, no-maintenance material which has the added advantage of being pre-measured. Use a carpenter's level during assembly to keep blocks level. The width should be 6' to 8' so that the bed is accessible from both sides. 8" to 12" height is usually adequate.

Creosote-treated railroad ties are not recommended because the creosote can leach into the soil for several years and continue to release vapors over a seven- to nine-year period. Young seedlings are likely to be killed if planted within six to ten inches of newly treated railroad ties for the first two to three years. It is unlikely, however, that the creosote is taken up by the plants. If it comes in contact with a root, it will simply kill the plant, thus eliminating its potential to absorb the material into vegetables or other plants.

Construction: Raised beds can be any size and any height. Add additional beds as your time and energy permit. A good size to begin with is 4' x 8' x 8" high. This size allows you to reach into the planting area to plant and weed without walking in it. The beds can be made as small as a 2' square for a small herb garden or as large as 8' x 16', and as high as you wish. The suggested 4' x 8' size frame makes it easy to buy, cut and assemble by making only one cut with a saw. You will need to purchase three boards of 2" x 8" and 8' long. Cut one board in half, giving you two 4' pieces for the ends. Nail these to the other two 8' long pieces. (Diagram on back)

Use galvanized nails (preferably with a twist in them) for better holding power. These nails are the type frequently used for building decks. Number 12 or 16 common would be a good size. Place no more than 4 nails in each corner. Drilling a hole a little smaller than the diameter of the nail will help keep the nails from splitting the board.

Soil Preparation: You will need a source of extra soil to fill the raised bed; this can be clay from a nearby area or purchased soil. Your finished soil should consist of a mixture of 1/3 organic material and 2/3 native soil. Begin the bed preparation by tilling or using a spade to break up the soil surface. Add the extra soil, plus 1 cup of 10-10-10 fertilizer and 2 cups of Dolomitic lime. Till the soil and all amendments until everything is thoroughly mixed.

Rake the prepared soil into a mound in the center. Place the frame as level as possible over the selected area, placing the rim on the firmer soil around the edges. Spread the soil inside the frame, adding amended soil until you get the height needed to bring the surface 1-2" from the top edge of the bed frame. Water the bed well and let the soil settle a few days. Smooth and plant as you would any other garden.