Why You Should Build A Raised Bed Garden

Today we have to deal with polluted and degraded soils, cramped urban environments, and a host of other problems that make growing directly out of the ground problematic in some areas.

Older civilizations dealt with some of these same issues, and came up with a method of improving their growing abilities.

By 300 B.C., the Quechuas of South America had deployed raised bed gardens to increase their yields while reducing soil erosion (1). Their system of raised beds and irrigation, which they called Waru Warn, had impressive results. It was successful enough that it's still being used in Bolivia and Peru today.

Today, building a raised bed garden offers solutions to host of issues, and they can be a valuable addition, and if nothing else, a fun experiment, for the casual gardener or determined farmer.

In its simplest form, a raised bed garden is just hard material holding a large portion of rich good soil off the ground for the purpose of vegetable, fruit, or ornamental plant production. Sometimes these containers are open to the ground on the bottom, but in the case of polluted soil, they're usually sealed off to prevent contamination.

Container materials can include rocks dug out of the ground, old bricks, cinder blocks, wood, and just about anything else you can imagine. While I'd be leery of planting edibles in them, I've even seen raised beds made out of old tires.

Construction is often as easy as stacking bricks or large rocks, but the raised beds can also be complicated and involve mortar and other materials.

You Can Build A Raised Ben Garden Almost Anywhere

If you live in a city or even in some suburbs, finding good quality land to grow on can be a problem. Most of the land that isn't used for buildings is paved over with cement and asphalt in deference to the almighty car.

Huge post-industrial brownfield sites that could have hosted large farms are rendered useless because the soil is polluted with dangerous chemicals. A raised bed garden can help solve these problems.

Any sunny surface you can find, no matter where it is, can be used for a raised bed garden. Unused parking spots, back decks, contaminated land, and even sturdy roofs can host one without a problem.

In these situations, you'll want to put a bottom in the bed to prevent contact between the soil and the ground.

Even if you have unpolluted land to plant in, some soils just won't cooperate.

Heavy clay or sandy soils can put a wrench in garden plans.

While it's usually possible to rehabilitate these sites with a massive sheet mulch application, some people just aren't interested in the work. A raised bed can save them a lot of time and disappointment.

High up in Africa's tiny country of Lesotho, the rain has two modes of arriving: in torrential downpours during the summer and not at all during the winter.

The soils are infertile, rocky, and thin, and the weather shifts between intense heat and fierce cold. Land cleared for planting usually cracks during the droughts and then washes away under the onslaught of winter rain. In short, agriculture is not easy.

While fruit tree cultivation certainly has the possibility of drastically improving the lives of people living there, when it comes to vegetables, a raised bed garden can make a world of difference. Luckily, one thing the country has in abundance is rocks, and people there are putting them to good use.

Check out how well a raised bed garden can work in Lesotho.

Raised beds have great drainage to keep them in good shape during deluges, and by covering them with straw or another type of mulch, they can stand up to a good scorching.

They're filled with manure, compost, and dirt, and so the problem of thin soils is bypassed. Because they're off the ground, they'll also never be stepped on and compacted, which is a significant problem in most gardens.

During the dry season they're kept wet with waste water from the households, and a compost heap in the center recycles food scraps into rich soil. As you can see, the vegetables that come out of them are large and look delicious.

If they can accomplish this in Lesotho, you can do it just about anywhere.

Because vegetables are usually grown quite close together in these raised bed gardens, with their leaves just barely seperated, they shade the soil more than in your average garden row.

This keeps the soil from drying out under the hot sun and also shades out many weeds. Due to the compact nature of the gardens, its easy to cover the soil with mulch, which will further hinder weeds, conserve water and protect the soil. A final weed deterrent deployable during construction is a barrier between the raised bed and the soil. This combined with the clean compost being used to fill the planter will ensure that weeds have a much harder time taking root.

If you use stones, bricks or concrete as your building material, they'll heat up during the day and emit that heat over the course of the evening. This can keep the soil temperature several degrees higher than you'll find in the regular ground soil, which can potentially extend your growing season.

This concept can be built on by placing old windows over the raised bed garden to create a greenhouse that will lengthen your growing season by at least a month before and after your area's frost dates.

The elderly and disabled will also enjoy a raised bed garden because they're several feet off the ground, which can make it easier for them to get to. But even the healthiest person will probably prefer not bending down so far to get to their salad.

The particular type of raised bed garden built in Lesotho is called a keyhole garden. Besides the above listed benefits, they're more efficient than the rows you typically find in western gardens.

In a traditional garden bed, we see single rows of plants interrupted by walkways, which take up about half the garden space. With a raised bed garden with paths going between every three or four rows, you cut down the space wasted with walkways to about 30 percent.

By making a raised bed into a circle or a horseshoe, even more space can be utilized.

When you wrap a typical 4 by 15-foot raised bed into a circle with a small opening for a path, you get the wasted space down from about 22 square feet - with an 18-inch-wide path down one side of the raised bed- to 6 square feet. With a circular raised bed, less than a quarter of the ground is surrendered to paths (2).

That quarter is usually in the form of the "keyhole," which refers to a small walkway that resembled a keyhole when viewed from above.

Having curves also eliminats the monotonous monoculture farm look, which I'm not a huge fan of. Even if you've got some straight lines, including a circle can add a bit of charm to your garden.

That the charm happens to be more efficient is all the better.

Most pieces of land are square or rectangular, so placing a circular raised bed garden along an edge can lead to waste if you don't plan correctly.

One interesting option is to face the opening of the keyhole south so it absorbs heat from the sun. This creates a perfect planting space for a heat-loving plant or two, which will bask in the heat the keyhole gives off.

This may cause problems for your walking path, but it's a great way to create an ecological niche.

If you want to make your own, check out these step by step instructions for building a raised keyhole vegetable garden here.

As you can see, raised bed gardens, particularly circular ones, have many benefits and are a great tool for any organic gardener.

The high-quality compost and amendments you can concentrate into them produces tasty crops and larger yields than you're likely to get growing in soil that hasn't been heavily improved.

Give one a try and you probably won't regret it.

Watch Andrew's video overview of his keyhole garden here.

Learn about a healthy raw food diet that will be improved by organic produce grown in a raised bed garden.

For more gardening articles, click here.

Raised Bed Garden Sources:

1) "Raised beds and waru waru cultivation." Organization of American States, Department of Sustainable Development.
2) Hemenway, Toby. "Gaia's Garden." pg 47.