How to create a raised bed garden

A raised-bed garden is a great alternative to grow healthy, delicious vegetables

Is your soil poorly drained or heavy clay? Not enough space for a full garden? Is bending or reaching an issue? A raised-bed garden may be a helpful solution to grow your favorite vegetables.

Watch our how-to video on constructing a raised bed garden or follow the instructions below:

Download the video transcript

Benefits of raised bed gardens

The benefits of raised beds are that they can be any shape or size to fit your needs, can be placed where your plants will get adequate sunlight, and can help you avoid soils with poor drainage, low organic matter, or heavy clay and rocks.

Raised beds and crop rotation

A series of raised beds allow gardeners to rotate crops annually from one location to another to reduce disease buildup in soils. For example, growing tomatoes in the same location year after year may allow fungal or bacterial disease such as early blight or fusarium wilt to build up and infect new plants. Extension recommends rotating plants and only return to the original growing location after at least three years.

If building a raised bed doesn’t sound appealing, many vendors offer pre-made beds or kits that require minimal assembly.

Considerations before starting a raised bed garden

1. Cost – you’ll need to make an initial investment into lumber and fastening hardware, weed barriers, and soil
2. Water – locate your bed with access to a water supply. Raised beds dry out faster than in-ground gardens
3. Temperature – raised beds are more subject to changes in temperature. They may heat up or cool down more quickly than the ground
4. Size – small beds may not support large crops such as melons or pumpkins
5. Material – wood beds may degrade over time and have to be replaced

Constructing your raised bed garden

We constructed a simple raised-bed garden with a budget in mind, and minimal use of hand tools. We also repurposed some materials such as our weed barrier to save on costs. The goal for this demo was to have the cost be under $100, to use all the lumber, and have less than ten cuts. We achieved this by making the dimensions of our bed match the length of the lumber as purchased. In this case, the purchased lumber was 8-feet in length, so we avoided having to cut the boards by making our bed 8-feet long. 

Before any lumber is purchased or cutting begins, a plan should be sketched, and the site evaluated for levelness, sunlight, and access to a water source. Make sure the dimensions have been double-checked so you only have to make one trip to the lumber yard.

Choosing lumber is important

We chose cedar lumber. Cedar contains oils and tannins that make the lumber naturally rot resistant. Untreated lumber is less expensive and can be used, but it will degrade faster. Untreated lumber exposed to the elements may last 3 to 5 years, while a cedar bed may last well past 10 years. Generally, we don't want to use pressure-treated lumber as it has historically contained chemicals that gardeners would not want leaching into the soil, though the regulations on those chemicals have changed in the past decade.

Tools you will need:

1. Handsaw, circular saw, miter saw, or table saw
2. Drill or cordless screwdriver
3. Fastening hardware (will vary based on board thickness)
4. Measuring tape
5. Speed square (optional but very useful for angles, straight-line marking, and cut support)
6. Clamps

Assembly:

We constructed these simple raised-bed gardens with a budget in mind, and minimal use of hand tools.

1. The dimensions of this bed are 8-feet long by 3-feet wide. Each side had a second board stacked on the top to make the bed 12 inches deep (6 inch board width). (You could get by with a  6-inch tall bed, but we wanted to grow carrots in the fall, and so made it a bit deeper to accommodate the root crop). We purchased a 12-foot board that was cut to comprise the 3-foot wide ends (4 cuts = four 3-foot sections). The corners were reinforced with a 2 x 4 that was ripped (cut longitudinally). For even more structure, brackets or 4 x 4 cedar posts can be used to anchor the corners and provide extra support. This demonstration only required 9 cuts for our final design. A larger or different shaped bed may require more sawing and initial costs. When using power tools or saws, make sure you've got some dust protection, ear protection, and eye protection.
2. Once the structure is confirmed, you can begin to clamp the lumber into place and fasten with outdoor wood screws. You can make a simple template with a piece of paper or cardboard to ensure your fastening screws don’t get drilled into each other. Space the location of your drilled holes to prevent intersecting screws and damaging the wood. We used eight screws on each corner to ensure a sound connection.
3. Once fully assembled and the site removed of existing weeds, the structure can be placed with the bottom of the bed flush with the soil level. Our corner and middle supports were buried approximately 4 to 6 inches and backfilled with soil.

4. Your lining material may need to be placed first, or you can place the lining into the bed to suit your needs. The only step left is to fill with a high-quality topsoil mixed with organic matter such as compost. Compost will help retain moisture, provide some nutrients, and will ensure your bed is well-drained. Once planted, you may also apply a layer of mulch two to three inches thick to retain moisture, suppress weeds, and protect plants from soil splashing onto the surface during rains, which may spread pathogens to your crops.

This design took one afternoon to construct and another hour or two to place the bed, prep the site, and fill with the soil mix. The materials cost approximately for $80 and another $20 or $30 for the soil mix. 

Related resources

Learn how to make a straw bale garden.