Build a raised bed in a weekend with basic tools and materials
A raised bed is a wooden or composite box filled with soil, built on top of the ground. You can build one in a day using four boards, corner brackets or screws, a drill, and a level. The most common size is 4 feet by 8 feet by 12 inches deep, though you can adjust the dimensions to fit your space and what you want to grow. The total cost for materials runs between $50 and $150 depending on wood type and whether you buy soil separately or use what you have.
The basic steps are: choose a location with at least six hours of sunlight, cut or buy pre-cut boards, assemble the frame, level it, and fill it with soil. Most people finish in four to six hours, including the time to let the soil settle. You do not need to dig out the ground underneath — the bed sits directly on grass or bare earth.
Key Takeaways
- A 4-by-8-foot raised bed made from untreated cedar or composite boards costs $50 to $150 in materials and takes one day to build.
- You need a drill, a level, a saw (or pre-cut boards), and four corner brackets or 3-inch screws to hold the frame together.
- The location matters more than the frame: pick a spot with at least six hours of direct sun and level ground, or level it yourself before assembly.
- Fill the bed with a mix of topsoil and compost rather than garden soil alone, because garden soil compacts and drains poorly in a confined space.
- Untreated cedar lasts five to seven years; composite boards last ten to fifteen years but cost more upfront.
Choose the right wood and size for your space
Untreated cedar is the most common choice because it resists rot naturally, costs less than composite, and looks finished. A 4-by-8-foot bed made from 2-by-12 cedar boards costs roughly $60 to $80 for the wood alone. Cedar lasts five to seven years before the wood begins to break down, especially at the corners where water pools.
Composite boards (made from wood fibers and plastic) cost $120 to $180 for the same bed but last ten to fifteen years with almost no maintenance. They do not rot, splinter, or need sealing. If you plan to keep the bed in place for more than seven years, composite pays for itself.
Avoid pressure-treated wood sold for outdoor decks. The chemicals used to preserve it can leach into soil over time, especially if you grow vegetables. Avoid railroad ties for the same reason.
Standard dimensions are 4 feet by 8 feet by 12 inches deep. A 4-by-4 bed works for herbs or flowers. If you are tall or have back problems, build it 18 to 24 inches deep so you do not have to bend as far. Deeper beds also drain better and give roots more room. Do not go wider than 4 feet — you need to reach the center from either side without stepping into the bed.
Gather tools and materials before you start
You need four boards (usually 2-by-12 lumber, cut to length), four corner brackets or 3-inch exterior screws, a drill with a screwdriver bit, a level, a tape measure, and a saw if you are cutting your own boards. Many home improvement stores will cut boards to length for free or a small fee, which saves time and ensures straight cuts.
For a 4-by-8 bed, you need two 8-foot boards and two 4-foot boards. If you buy 2-by-12 cedar, the lumber yard can cut them while you wait. Bring a list of your dimensions so the cuts are accurate.
For fasteners, corner brackets (L-shaped metal pieces) are the easiest method if you have never built anything. Drill pilot holes, then screw the bracket to both boards. Alternatively, use 3-inch exterior wood screws driven at an angle through one board into the end of the next. Exterior screws resist rust better than standard screws.
Assemble the frame on level ground
Lay the four boards in a rectangle on the ground where you want the bed to sit. Before fastening anything, use a level to check that the ground is flat. If one corner is higher than the others, dig out soil from the high spots or add soil to the low spots until the frame sits level. This step prevents water from pooling in one corner and soil from washing out.
Once the ground is level, attach the corners. If using brackets, position the bracket on the inside corner, drill pilot holes through the bracket into both boards, then drive screws through the bracket into the wood. If using screws alone, drive them at a 45-degree angle through the end of one board into the side of the other, using at least two screws per corner.
Check the frame with the level again after fastening. If it has shifted, loosen one corner and adjust. A level frame is easier to fill and keeps soil from eroding unevenly.
Fill the bed with the right soil mixture
Do not use garden soil straight from a bag. Garden soil is dense and compacts in a raised bed, which blocks drainage and root growth. Instead, mix topsoil and compost in roughly equal parts, or use a ratio of three parts topsoil to one part compost if compost is expensive in your area.
A 4-by-8-foot bed that is 12 inches deep holds about 32 cubic feet of soil. You can calculate this by multiplying length × width × depth in feet, then dividing by 27 to convert cubic feet to cubic yards. Most bags of topsoil or compost are 2 cubic feet, so you will need about 16 bags. Buying in bulk from a landscape supplier is cheaper than bags if you have a way to transport it.
Fill the bed to within an inch of the top. The soil will settle over the first week or two, so do not fill it completely. Water the bed after filling so the soil compacts and you can see where it settles. Add more soil if needed after a few days.
Protect the wood and prepare for planting
Cedar does not need sealing, but you can explore a natural oil finish if you want it to look polished. Do not use paint or stain — they can peel and flake into the soil. If you use composite boards, no finish is needed.
Before planting, let the bed sit for a few days so the soil settles and any air pockets collapse. If you are planting vegetables, wait at least a week after filling so the soil has time to stabilize. You can plant flowers or herbs when ready if you water them well.
Consider adding a landscape fabric or cardboard layer at the bottom if you are concerned about weeds coming up from underneath. Lay it flat before filling with soil. This step is optional — many gardeners skip it and pull weeds as they appear.
Maintain the bed and replace boards when needed
Cedar boards typically last five to seven years before rot becomes visible at the corners and along the bottom edge. You can extend the life by keeping the bed well-drained and not letting water sit against the wood. If one board rots before the others, you can replace just that board without rebuilding the entire frame — loosen the corner brackets or screws, slide out the damaged board, and slide in a new one.
Composite boards require almost no maintenance. They do not rot, splinter, or need sealing. Over time, they may fade slightly in color, but the structural integrity remains intact for ten to fifteen years or longer.
Refresh the soil every two to three years by adding a 2-inch layer of compost on top. This replenishes nutrients and improves drainage as the original soil compacts.
Frequently Asked Questions
Can I build a raised bed without corner brackets or screws?
Yes. You can use wooden corner posts — 4-by-4 pieces cut to the height of your bed — and screw the boards to the posts instead of to each other. This method is stronger and lasts longer because the joints are reinforced. It costs a bit more in materials but is worth it if you plan to keep the bed for many years.
What if my ground is not level?
Level it before you build. Dig out soil from high spots or add soil to low spots until the ground is flat enough that a level rests evenly across the frame. If the slope is steep, you can build the bed on a slight angle and accept that one side will be slightly higher — just make sure the frame itself is level so water does not pool.
How deep should a raised bed be for vegetables?
Twelve inches is the minimum for most vegetables, but 18 inches is better for root crops like carrots and potatoes. Shallow beds work for lettuce, herbs, and flowers. Deeper beds also warm up faster in spring and stay cooler in summer because the soil mass is larger.
Can I use reclaimed wood or pallets?
Reclaimed wood can work if it is not pressure-treated or painted. Pallets are risky because many are treated with chemicals to prevent mold and insects during shipping. If you use pallets, choose ones marked "HT" (heat-treated) rather than "MB" (methyl bromide). Cedar or composite is safer and not much more expensive.
Do I need to line the bottom of the bed?
No, unless you are concerned about burrowing pests like moles or voles. Landscape fabric or cardboard at the bottom slows weeds but is not required. Most gardeners skip this step and manage weeds by hand or mulch.