Raised Bed Gardening
Posted: April 26, 2012
Raised beds can be made very simply by mounding up soil to a certain height and width; or they can become very involved: box-like structures made of wood, stone, brick, or blocks, with fencing, screens, watering systems, and grids to organize plants in precise patterns. If you use old pressure-treated lumber or railroad ties to construct a raised bed, it is important to create a barrier between the wood and the soil to prevent leaching of any chemicals into the soil.
Why use raised beds? Raised beds are a form of no-till gardening that promotes soil enrichment and healthy plant development. As you “raise your garden bed” by building up the soil with compost, manure, leaf mulch, and other materials, over time your soil will have excellent friability, the ideal “chocolate cake” of soil, and tilth, a term used to describe the “workability” of the soil. Your soil will also have excellent drainage. Raised beds lessen soil compaction because you will not bewalking or using heavy equipment on the soil, again promoting friability and tilth. Make your raised beds four feet or less in width and about eight feet in length for easy access from all sides.
Soil in raised beds warms up more quickly in spring. Good tilth and excellent drainage hasten soil warming, which allows for earlier planting of cool season crops.
Raised beds also make an excellent foundation for intensive and succession planting, allowing for a larger yield in a smaller space. I plant in a grid or broadcast fashion instead of in rows with bare ground in between. Grid planting—square-foot gardening is an example—divides the planting space into blocs, each planted with a certain number of plants depending on that plant’s growth habits and space requirements, leaving no room for weeds.
An example of broadcast planting is my “salad garden.” I mix several different seeds of lettuce, radish, red beets, spinach, and other greens together and then broadcast the seed in a portion of my raised bed. When I harvest, I already have a “tossed salad”!