Raised gardening beds

Raised bed gardening is a form of gardening in which the soil is formed in 3–4 foot (1.0 m) wide beds, which can be of any length or shape. The soil is raised above the surrounding soil, and enriched with compost. The beds are enclosed by a permanent frame, which is generally made of wood, rock, or concrete blocks. The vegetable plants are spaced in geometric patterns, much closer together than conventional row gardening. The spacing is such that when the vegetables are fully grown, their leaves just barely touch each other, creating a microclimate in which moisture is conserved and weed growth suppressed. Raised beds produce a variety of benefits: they extend the planting season; they reduce the need to use poor native soil; and they can reduce weeds if designed properly. Since the gardener does not walk on the raised beds, the soil is not compacted and the roots have an easier time growing. The close plant spacing and the use of compost generally result in higher yields with raised beds in comparison to conventional row gardening.

Typically, raised beds are laid out in a rectangular shape, but any shape is acceptable. Smaller square or triangle-shaped beds can be used in spaces that are too small to accommodate a full size bed. After the initial construction process, raised beds require less maintenance than conventional garden beds.

Higher yields

Raised beds are approximately twice as productive per square foot of space as conventional row planting. Traditional gardens consist of long, single rows of vegetables spaced widely apart. Vegetables are planted just far enough apart to avoid crowding. Because they are planted closer together, you lose some productivity per plant, but as more plants are being grown in a smaller space your overall yields will be higher. Grow a variety of different plants in the bed, and when you harvest one plant, plant something new in the same spot.
Another advantage of raised beds is that because no one walks on the soil, it does not become compacted. This means that root growth is greatly improved, so plants grow is more vigorous which leads to higher yields.

Longer growing season

The soil in raised beds warms earlier in the spring than the surrounding ground, which allows you to plant in raised beds about one months earlier than if you where planting directly into the ground.

Make sure that the area has easy access to water sources as well as room for you to work.

The downside

Possibly the most significant problem with raised beds is their tendency to dry out. Typically a raised bed will require twice as much water per square foot as a conventional garden; however, they also grow twice as much food per square foot, so it balances out. As watering is increased, nutrients can be flushed out of the soil rather quickly, so it may also be necessary to increase the application of fertilizer as watering increases.

Watering should be done early in the morning or in the evening rather than the middle of the day, as water evaporates more quickly during the afternoon. Also using mulch, such as straw or hay, is highly recommended as this will decrease the amount of water lost through evaporation.
Soaker hoses and drip irrigation systems are well suited to raised beds. They also reduce disease by directing water to the soil instead of wetting leaf surfaces as with overhead irrigation.

Using difficult sites

Raised beds make gardening possible on sites where growing plants would otherwise be impossible. Rooftop gardens and raised beds on top of concrete are examples. You can place a raised bed directly on top of an existing lawn, without removing the sod underneath.

Choose a location

The bed should run north to south lengthwise for maximum sun exposure. If your bed must run east to west, place the taller plants on the northern side of the bed; this will minimize shading. The exception to this rule is terraced raised beds which should be oriented with the slope, to minimize erosion.

How large?

A bed 4 feet wide by 15 feet in length and filled with 8 inches of soil is ideal. Beds should be no wider than 4 feet, a size small enough to work in without having to step onto the bed. Some people prefer 3 foot wide beds, it really depends upon what you are comfortable with. If the bed is too wide you will find yourself walking, kneeling, or leaning on the soil, which defeats a major advantage raised beds have over traditional gardens. And you don't want the bed so wide that you have to strain to reach the center areas, play it smart, keep it thin and workable. Beds placed against a wall or fence should be no more than two feet wide.

Beds can be any length you desire, they can run 100 feet in length if that's what you want. But from a practical standpoint, most people opt for beds of 8, 10, 12, or 15 feet in length. Leave 2 to 3 foot wide walkways between the beds, so there is room for a wheelbarrow or garden cart.

Soil

As a rule of thumb, when starting a raised bed use a mixture of one part compost to two parts topsoil (one pound of compost for every two pounds of topsoil). If you have access to well rotted manure, add that as well. The soil in the bed should be at least 8 inches deep or higher than whatever ground the bed is built upon.

In-between your soil and the existing ground, place a layer of cardboard or 4 layers of newspaper. This layer will suffocate the existing grass or weeds as the soil pushed down on it, and in time it will decompose and become part of the soil.

Materials for building

Avoid treated lumber as the chemicals in the wood can potentially seep into the soil and end up in your food, same goes for anything coated with creosote. Popular material include 4 x 4 timbers, 2 x 6 lumber, and concrete blocks. Concrete blocks can be stacked up to 2 feet high without using mortar, if they are offset.

Not every plant is meant to be grown in a raised bed

Some vegetables , such as squash, melons, pumpkins, and sweet corn are not recommended for raised beds due to the extensive space they shade. It is easier and just as effective to grow these on the ground and not in a raised bed.


This page uses some content from the English-language version of Wikipedia. The original Wikipedia article was at Raised bed gardening. The list of authors can be seen in the page history. As with Perma-Cairn, the text of Wikipedia is available under the Creative Commons Attribution-ShareAlike License.

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