How To Build A Raised Bed Garden Box

So you want to build raised garden beds and you're wondering which system is best for you. Should you go with a pre-fab kit or start from scratch? Here's what you need to know.

There's no question that raised beds are popular for a reason. Not only do they look stunning in a backyard garden, they also ease the workload that comes with maintaining traditional, in-ground beds. Unfortunately some raised bed systems are costly to buy and time consuming to install. But not all raised bed systems are the same.

Whether you're handy with tools or don't know a drill press from a driver, there are kits on the market that are easy to build with little time or expense. There are also do-it-yourself options if you have the time or the inclination.

So why should you bother assembling or building a raised bed garden?

Benefits of raised bed gardening

There are a lot of great reasons to build raised beds that contain and protect your garden soil.

Less tilling

Raised garden beds require less tilling than traditional, in-ground beds. Instead of digging up a compacted bed year after year, many gardeners add compost and other soil amendments to the top of their elevated beds in fall, then let nature do the rest over the dormant season. This is a good practice for both soil and plants.

Easier on your back

Bending, stooping, and kneeling can all take its toll on your back and joints. Raised bed designs come in a variety of heights to make reaching your crops less stressful on your body over time.

Nice to look at

In the backyard or the front, a series of raised planters surrounded by paths looks neat and well tended all year round.

Controls weeds and keep out critters

Raised garden boxes are known to deter rabbits, which will handily nibble in-ground crops growing at eye level. They also make it easy to install copper slug 'fencing' and other deterrents around the perimeter. Raising your beds also means moving crops away from dogs that may otherwise (ahem) urinate on your garden. If you have weed problems, you can install a weed barrier beneath your bed's soil at installation time to ensure invasive weeds or tree roots don't invade the bed.

Improves drainage

If your garden soil is normally wet into springtime, elevated beds solve this problem by lifting the soil above ground level and giving your plant roots room to breathe.

Offers a head start on the growing season

Raised beds filled with nutrient rich, organic soil warm faster in spring due to their elevation away from the cold ground—and their improved drainage. In this way, beds built 12 inches deep or more have the added benefit of giving plants a longer growing season.

For more benefits, see 10 Reasons to Add Raised Garden Beds to Your Garden.

Pre-fab raised garden bed kits

If you don't have the time or resources to muster the raw materials for building a raised garden bed from scratch, you can purchase one of the easy-to-assemble kits on the market. In this case, your first consideration should be the type of materials available and how quickly and easily they go together.

Natural wood

Some of the least expensive kits are made from raw, natural wood or wood treated with natural wood stabilizers. (Avoid pressure treated lumber.) Cedar is the most common wood used for raised beds because of its durability and resistance to rot. It's also lighter to handle than many other woods. Two cedar boxed garden systems that assemble in minutes are detailed below.

Farm Style Raised Garden Beds

These easy-to-assemble beds are made from Vermont white cedar. Stack them together in minutes without tools, fill with soil, and your garden is ready to go. They will last for many years and weather to a soft, silver grey.

farmstead raised garden beds with plants

Natural Cedar Beds

Like the kit above, these beds are made from natural cedar and assemble in minutes without tools (unless you opt for the version that includes trim). The main difference is that the boards in this system are Oregon incense cedar treated with a natural silica-based stabilizer. Both kits come in a variety of sizes and shapes.

natural cedar raised beds

Composite lumber

Next in terms of price are kits made from a blend of hardwood fibers and post-consumer recycled plastic. Approved for organic growing, these kits are durable, light, long lasting, and easy to assemble. They also resemble natural grain wood in color and texture. The reason they cost a little more? Wood composite is warp resistant and maintenance free. They will look the same for years without interventions.

Composite Raised Garden Bed

This composite bed takes about thirty minutes to put together. Assembly involves sliding each timber into a joint and fastening with zinc-plated screws (provided with the kit). The joints each have stake that needs pressing into the ground.

composite garden boxes made from hardwood and recycled plastic

Recycled plastic

The final type of raised garden kit on the market is made from recycled plastic. These kits are the longest lasting and share the same low maintenance features as the composite lumber beds above.

Recycled Plastic Raised Garden Beds

These beds are made from 100% HDPE (high density polyethylene) plastic, the same material that you find in high quality garden furniture and public picnic tables. They are easy to assemble in about 20 minutes and don't require any tools to put together. They're also available in five colors, which means you can match them to your backyard décor for a seamless blend. Each non-toxic color includes UV protection to minimize fading over time. And speaking of time, these kits come with a 50 year warranty, which is pretty hard to match.

recycled plastic raised garden bed

While there is no clear winner in terms of materials, wood beds biodegrade at the end of their lifespan, meaning no waste gets left behind. That biodegradable capacity means they won't last as long as synthetic materials, however, so if durability is your goal, a composite or recycled plastic bed is a good alternative option.

For more discussion about the merits of different raised bed materials, read our article Cedar vs. Recycled Plastic vs. Composite Raised Garden Beds

DIY home-built raised beds

Building your own elevated garden boxes is a straightforward project for anyone with access to materials, along with the space and skill to fashion the parts. Here are some things to consider before you build your own raised beds.

Best wood choices

As noted above, cedar is one of the most rot resistant woods available. It's also lightweight enough to handle for one person if dried thoroughly. Other options include black locust and redwood. If these are too expensive in your area, consider using fir or spruce, with the understanding that they will not last as long. You can also ask your local lumberyard what they recommend. Recycled boards repurposed from other projects are another lower cost option, as long as they aren't treated. Avoid pressure treated wood and pressure treated lumber.

Use standard sizes, starting with 2 x 6 for the most basic bed with good soil underneath, all the way up to 2 x 12 if you need a taller bed for plants with deeper roots. You can also stack your lumber in tiers.

In general, most garden vegetables need 12 – 24" of soil depth to grow, with a few others needing as much as 36" of depth. (For the needs of specific garden crops, see our table of soil depth requirements.) If you have 12" of usable soil beneath your bed, build up another 12-24" to accommodate the crops on your list.

To stain or not to stain

The woods listed above will last a long time (10-20 years depending on your climate), but they will biodegrade eventually. To slow this process, you can treat your boards before building your beds, but be sure to use a non-toxic wood treatment that won't leach harmful chemicals into your soil—and potentially your plants. Avoid buying pressure-treated or stained wood, unless it's specifically designed for using in and around garden beds.

Hardware and other materials

Many screws are made from metal that will leach a dark stain onto wood when exposed to moisture. To avoid this, use coated deck screws or stainless steel. Pre-drill all holes to prevent your wood from splitting.

Simplest raised bed corners

pre-fab anchor joint for raised bed corner
To simplify the job even further, you can purchase pre-made anchor joints for your garden box corners. These brackets feature an 11.5" stake that can be hammered into the ground, making fastening your corners a breeze.

Stacking brackets also exist for the upper levels of tiered beds.

Bracing your beds with crossbeams

For beds longer than 8', we recommend installing cross supports to prevent bowing outwards from the weight of your soil. Use ½" aluminum flat stock cut to match the inside width of your bed.

Building raised beds from alternative materials

Concrete blocks, bathtubs, metal feed troughs and even old canoes can all work for instant raised garden beds. Just be sure your creative choices don't expose your soil and plants to toxic chemicals from paints, stains, or other finishes.

Simplest DIY raised garden bed design and instructions

The following instructions demonstrate how to make a simple raised bed with basic materials. This is the design our founder and his family have used in their garden for over 40 years.

The plans make one 4 x 8' raised garden bed. You can extend the length to fit your space, but if your bed is going to be longer than 8', you'll need to add extra posts mid-span to prevent bowing and to provide a place to secure cross supports. See note above about bracing your beds with crossbeams.

To further strengthen your bed, consider using full dimension lumber, also known as "nominal" lumber. This is lumber cut to the full two inches thick and (in this case) six inches wide, instead of the standard cut you will get if you purchase from a commercial supplier (which will be slightly smaller due to shrinkage and planing). You can buy dimensional or nominal lumber from a local mill.

If you're building on a slope, see our article about How to Build a Raised Garden Bed on Sloping, Uneven Ground.

DIY How to Build a Simple Raised Garden Bed

Materials needed:

Four 8' 2 x 6″ cedar boards
Four 4' 2 x 6″ cedar boards
Four lengths of 4 x 4″ lumber, cut about 15" long, for corner posts
16-24 coated deck screws, size 3.5"#10

Tools needed:

Hand saw
Carpenter's square
Level
Drill
Driver

How to build Your bed

After leveling and clearing the area where your bed will be located, lay out the bottom tier of your beds using two 4' 2 x 6s, two 8' 2 x 6s, and your four corner posts. It's not necessary to cover the ground with landscaping fabric.

Starting with first corner, attach frame to corner post using two screws per side, leveling as you go. Continue with remaining three sides until you have one complete row.

Add the next row of 2 x 6' boards, screwing to the corner posts as above. Level the entire bed. You may have to dig in places to get your bed to level.

Cut off corner posts flush with top of frame. Smooth ground around bed and fill bed with soil. Now you're ready to plant!

DIY or kit: which type of raised garden bed is best?

When should I use DIY?

When you have the time and skill to make your own, DIY raised garden beds are often the most economical choice. And while pre-fab kits come in a variety of sizes, you can make DIY beds to fit tricky spaces and unusual depths.

When should I use a pre-fab kit?

If you need your bed to go together quickly, if you don't have the tools or space to make your own, or if you need a long-lasting plastic or composite system that's easy to clean and move, a pre-fab kit is the better choice for your situation.

Getting the most from your raised bed garden

Whatever you choose, raised gardens are a satisfying way to grow your own food without the strain and stress on your body. Here are some other tips to remember when using your beds.

Fill your beds with the best soil possible. Avoid buying topsoil, since it usually lacks the nutrients and structure needed for gardening. Instead, look for soil labeled "triple mix" (a mix of topsoil, rotted compost, and peat moss) or garden soil. And beware of adding anything to your beds that may contain weed seeds (unprocessed manure, unfinished compost, etc.) It's not necessary to use landscaping fabric at the bottom of your bed.
If the ground beneath your bed has never been used for gardening, you can prepare it by turning over to a depth of about 16 inches deep. This will create better conditions for plant roots that need extra depth to grow.
If you live in an area where burrowing pests are a problem, add a layer of hardware cloth (or another fine metal mesh) across the bottom of your garden bed and about 3" up the insides. If other pests affect your area, read How to Keep Animal Pests Out of Your Garden.
Avoid compacting your soil once it's in place. Stepping on the soil will compress the air pockets needed for plant roots to take up water and nutrients. Instead, use a spanner board (a board that spans your bed from edge to edge) if you need to cross. In general, beds that are no more than 4' across are usually easiest to access.

Editor's note: this article was originally published in 2019 and has been updated for accuracy and comprehensiveness.

About the Author

Shannon Cowan
The blog editor at Eartheasy.com, Shannon lives on six acres of land with her husband, daughters, and backyard poultry flock.