How To Build and Maintain Raised Beds

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Have you ever wanted to garden but the odds are stacked against you? Perhaps your soil is rock-hard or pure sand. Perhaps your growing season is very short. Perhaps you live in a dry desert environment. Perhaps burrowing pests such as voles routinely decimate your vegetables. Or perhaps your back or knees are too fragile to handle the workload required to coax plants from the ground.

Whatever issue you face, it’s very likely the solution involves getting the vegetables into raised beds, however “raised beds” is interpreted. Because make no mistake, there has never been a more flexible and widespread system of growing a garden than getting the garden off the ground and into dedicated containers.

History of Raised Bed Gardening

We like to think raised-bed gardening is a fairly modern development, but in fact, raised beds go back hundreds or thousands of years in various cultures.

  • In Mesoamerican agriculture, small rectangular areas of fertile land on shallow lake beds in the valley of Mexico were called “chinampas”, created by interweaving reeds with stakes beneath the lake’s surface.  Soil and aquatic vegetation were piled into these underwater fences until the top layer was visible on the water’s surface.  Then, using a system of ditches and drainage, the planting bed became more pronounced as well as increasingly fertile by amending it with nutrient-rich lake-bottom silt.
  • The pre-Hispanic people in the Andres region of South America developed a technique called “waru waru” which employed similar principles.
  • The Zuni Indians in the American desert Southwest used a “waffle garden” technique which channeled water to plant roots through a simple design of sunken squares walled by low rims of soil.
  • In ancient Thebes and ancient Egypt dating to 4,000 years ago, tomb walls were illustrated with raised rectangular “funerary beds”, which were likely planted with shrubs, trees, lettuce, and herbs. Archaeologists recently discovered physical remains of these beds.
  • Hügelkultur, the progress of using decaying biomass to provide nutrition underneath mounded beds, was practiced in German and Eastern European societies for centuries and has enjoyed a modern renaissance.

In some respects, modern raised-bed techniques are really nothing more than reinventing the wheel of ancient practices used to wrestle food from uncooperative environments.

Benefits

There are a lot of benefits of raised bed gardening. They reduce back and knee strain (try sitting on a crate or stool to weed, rather than bending over the beds).  They warm the soil earlier in the spring and provide better drainage. They keep weeds out of pathways. They maximize growing capacity in smaller spaces. They prevent soil compaction and soil erosion.  The soil stays friable. The gardener is better able to control the type of soil and amendments filling the beds, resulting in increased fertility (it’s easier to amend the soil in the raised beds than amend the soil in the ground).

A distinction should be made between raised beds – which are open to the ground – and raised containers, which have closed bottoms (though still permitting drainage). Both kinds of beds provide similar benefits, though raised containers can be used on patios or other areas with no direct ground contact.

Disadvantages

Of course, nothing is perfect.  Raised bed gardens cost more for materials, take more work to construct, and require managed watering through drip irrigation or some other artificial means (since water will drain more readily). If your health is fine and if your soil is fertile, friable, and forgiving, then raised beds may not be necessary.

But the popularity of raised beds can be attributed to the fact that the advantages outweigh the disadvantages – sometimes enormously. Raised beds are particularly suited to areas where conventional gardening is challenging due to a short growing season, or dry desert climates, or poor soil conditions, or endless other problems. Personally speaking, we tried for nine years to garden in our tough clay weed-infested soil and failed every time. It wasn’t until we put in raised beds that we became almost entirely self-sufficient in fruits and vegetables within a short span of time.

Raised Bed Construction

Raised bed construction lends itself to endless creativity.  All that matters is elevating the beds above the ground level.  The simplest raised beds are just mounded dirt (often by double-digging), amended with compost and (sometimes) sand. However, most raised beds rely on some sort of structural support to contain the soil.

Depending on your finances, raised beds can be created using stylish new materials or stuff that’s scrounged for free.  Beds can be made from woven branches, tires, bricks, cinder blocks, boards, hay bales, sheet metal, fencing, pallets, logs, sandbags, stone, railroad ties, corrugated stock tanks or culverts, steel, concrete, recycled plastic, even “upcycled” dresser drawers…in short, anything that offers strength and support to hold in the soil. We even pressed an old wooden rowboat into service; for the past eight years, our “garlic boat” has grown the most wonderful and abundant garlic.

Additionally, raised beds can be any shape: square, rectangular, oval, circular, triangular, serpentine…whatever fits your space, resources, and imagination.

The University of Florida’s Gardening Solutions website issues some cautions when selecting material for raised bed construction:

  • Avoid the use of creosote or pentachlorophenol-treated lumber for bed frames. These chemicals can leach out and injure plants.
  • Landscape timbers and railroad ties may have been treated with compounds that contain arsenic. New lumber is no longer treated with those compounds, so using new lumber whenever possible is recommended.
  • If you’re uncertain about the safety of treated lumber, place a heavy plastic liner between the treated lumber and soil used for growing plants to prevent direct contact of plant roots with the treated lumber. Be careful not to tear the plastic when tilling the bed.

While construction methods will vary depending on what materials are used, a few good pointers are as follows:

  • This is one project where advanced planning pays big dividends. Start with a piece of paper.  Sketch your garden space (or in our case, get a Google Earth overhead snapshot) and plan in advance where your beds will go. Plan their orientation to take maximum advantage of the sun.  Decide on the quantity and shape of the beds. Establish how wide you want the paths between the beds to be (hint: it’s nice if wheelbarrows will fit). The time to mess up the garden is while it’s still in the paper stage.
  • Don’t make the beds so wide you can’t comfortably reach the middle. Four feet should be your maximum width, with three feet wide a more comfortable width for short people (like me).
  • The ideal depth is between 12 and 24 inches, depending on how deep are the root systems for your destined plants.
  • While some people recommend making the edges of the beds wide enough to sit on for ease of weeding, I’ve found the sideways sitting position makes weeding awkward, since I use both hands for the task. Instead, I sit on a plastic crate which I move around as needed, to make weeding comfortable.
  • Be careful of installing raised containers on wooden decks; the weight of the soil may cause structural problems.
  • Since you’re starting “fresh” with the contents of the raised beds, now is your chance to make the soil as rich, friable, and fertile as possible. Some people recommend filling the beds with potting soil, but depending on the size of your garden, that can become ridiculously expensive.  Instead, consider adding topsoil, sand, and compost to create a high-quality mix. We literally brought in topsoil and sand by the dump truck-full, which we mixed with our own compost (created from cattle manure). You can amend the soil with organic matter and nutrients as you go.
  • Keep the beds in a north-south orientation. This allows direct sunlight to reach both sides of the beds. The exception may be for taller crops such as corn, caged tomatoes, or trellised plants such as peas or pole beans. These might do better on an east-west orientation.
  • Place weed deterrents at the bottom to prevents weeds or grass from growing up through the new beds. Corrugated cardboard or several layers of newspapers are inexpensive options.  Additionally, placing metal hardware cloth at the bottom will help deter burrowing pests such as voles and gophers.
  • Raised beds lend themselves very well to covering, either with netting (to protect against hungry birds) or plastic (to create cloches for frost protection).

Maintenance

Personally, I think raised beds are easier to maintain than an in-ground garden, but that doesn’t mean they’re maintenance-free.

  • Watering. Since raised beds drain well, they require regular watering. Depending on how your garden is arranged, drip irrigation may be an ideal solution (it is for us). Soaker hoses may also work. Overhead watering may lead to diseases, especially in humid climates, so use this option judiciously.
  • Mulch. Because of the easy drainage in raised beds, mulch is highly recommended. Not only will mulch suppress weed growth, but it will slow water loss. Many different types of mulch are available, including bark, wood chips, cocoa bean hulls, leaf mulch, dried grass clippings, newspaper, straw, and compost. From personal experience, I prefer not to use hay mulch, as it often contains seeds which sprout, grow, and take over beds. We use pine needle mulch (which, contrary to popular belief, is NOT acidic).
  • Weeding. No matter how perfect your raised beds, you’ll still get weeds (the seeds of which can often be blown in from elsewhere). Thankfully the soil in raised beds remains far more friable than in the ground, so weeds are easier to pull. Mulch will also help suppress weeds.  Many people prefer weeding in raised beds since the smaller units are less overwhelming than trying to weed an entire garden. You can weed just as many beds as you have the time or energy for.
  • Settling. Whatever soil mixture you put in your raised beds, expect a certain amount of settling.  This is normal; however, it means you’ll have to supplement the beds every other year or so.

What Grows in Raised Beds?

Raised beds are so versatile and functional that I simply could not find anything that would NOT grow. In our case, we grow corn, beans (both green and dry), tomatoes, broccoli, brussels sprouts, cucumbers, zucchini, squash, onions, garlic, strawberries, blueberries, raspberries, carrots, bell peppers, cayenne peppers, pumpkins, watermelons, cantaloupe, peas, grapes, potatoes, seed poppies, and herbs (oregano, basil, horseradish, spearmint, rosemary, parsley, thyme, sage). Because our tough clay soil is so unforgiving, we even grow fruit and nut trees in tall raised beds: peach, apple, plum, and hazelnut. Excluding the orchard, our garden is about a quarter-acre in size, and raised beds have allowed us a degree of food self-sufficiency that would be otherwise impossible in our challenging soil and short growing season.

Raised beds lend themselves to intensive gardening. According to Rodale’s Organic Life “Intensive gardening methods all have their own disciplines, but all use raised growing beds, close spacing between plants, careful attention to building and maintaining soil fertility, and succession planting to make the best use of available growing space.”

With skillful application, intensive growing methods often produce harvests 4 to 10 times greater than conventional row gardening, though of course such techniques also require more initial work, planning, and scheduling. However intensive gardening simply isn’t possible directly in the ground unless heavily amended with compost, sand, or other amendments. In fact, the four principles of intensive gardening are:

  1. Permanent garden beds
  2. Reliance on compost
  3. High-density mixed planting
  4. Prompt succession planting

Quite simply, this kind of gardening technique would be virtually impossible without the use of raised beds.

Adapt to your Circumstances

One of the most disheartening and discouraging things you can do is try to make your garden look like those flawless photos you see on Pinterest. Let’s face it, most of us aren’t perfect, and neither are our gardens.

Instead, you’ll have to adapt your gardening efforts not only to your climate but to whatever other circumstances you face: yard space, health, time, finances, climate, etc. One of the beauties of raised bed gardening is its flexibility to conform to any of these challenges.

In our case, we have a very short growing season and tough, almost impenetrable clay soil. Our raised beds (technically, raised containers) allows the soil to warm sooner and bypasses the clay conditions. We can net the beds against birds or cloche against an early frost.

Other people face different challenges, whether it’s sandy ground, or dry desert, or specific pests or diseases. Whatever issues you face, talk with other local experts (successful gardeners, agricultural extension agents, nurseries) to learn any regional tips of the trade: preferred cultivars, best plant-by dates, first frost dates, etc.

Start Small, Grow Big

Because raised beds take time, effort, and money to install, it’s recommended you start small.  We began with four beds built from scrounged barn beams. The results were so impressive that we knew this was the way to go for us. Five years later, our raised-bed garden is a quarter-acre in size and provides nearly every fruit and vegetable we consume, with plenty for preserving and giving away.

And all it took was getting the plants off the ground.

Raised beds are a flexible and widespread system of growing a garden by getting it off the ground and into dedicated containers. Learn how to build and maintain them.
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