What You Need to Build a Raised Bed
A raised bed is a wooden or composite box you fill with soil and plant into. To build one, you need four boards (usually 2 inches by 8 inches or 2 inches by 10 inches), four corner brackets or screws, a drill or screwdriver, a level, and a location with at least six hours of direct sun. Most people choose untreated cedar or composite boards because they resist rot longer than pine or treated lumber.
The boards form the walls. The brackets or screws hold the corners together. You do not need a foundation—the bed sits directly on grass or soil—but you may want landscape fabric on the bottom to block weeds. The whole assembly takes one to two hours for a beginner.
Standard raised beds are 4 feet by 8 feet and 8 to 12 inches tall, though you can make them any size that fits your space. Taller beds (12 inches or more) are easier on your back and drain better. Wider beds should not exceed 4 feet across, or you cannot reach the center without stepping into the soil.
Key Takeaways
- Untreated cedar or composite boards last longer than pine and are safer for vegetables than pressure-treated lumber.
- Corner brackets or 3-inch deck screws hold the frame together; brackets are faster if you do not own a drill.
- A level ensures water drains evenly and soil does not pool on one side.
- Landscape fabric under the bed blocks weeds but is optional if your grass is thin.
- You can build a basic 4-by-8-foot bed in one to two hours without special tools.
Choosing Your Location and Preparing the Ground
Pick a spot that gets at least six hours of direct sun—more if you are growing vegetables. Avoid areas under trees or next to buildings that cast afternoon shade. The ground should be relatively level; a slope of more than a few inches will cause water to run off one end.
Clear the grass and weeds from the area where the bed will sit. You do not need to dig deep—just remove the top layer of sod and dead leaves so the boards sit flat on bare soil. If the ground is very uneven, you can level it by removing high spots and filling low spots, or you can use shims (thin wood wedges) under the boards as you assemble.
Check that the spot drains well. If water pools there after rain, the bed will become waterlogged. If drainage is poor, you can build the bed slightly higher or add a layer of gravel under the landscape fabric to help water move away.
Assembling the Frame
Lay the four boards on the ground in a rectangle. If you are using corner brackets, position them on the inside corners and screw them to both boards at each corner. Most brackets come with four to six pre-drilled holes; use at least four screws per bracket. If you are using deck screws instead, drill a pilot hole (a small starter hole) through one board into the end of the other, then drive a 3-inch screw through. Use two or three screws per corner.
As you tighten the corners, check that the frame is square by measuring diagonally from corner to corner—both diagonals should be the same length. Once the frame is square, place a level on top of each board and adjust shims underneath until the bed is level in all directions. This step matters because water will drain to the low side and leave that end drier than the other.
If you are building a bed longer than 8 feet, add a support board down the middle to prevent the long sides from bowing outward when filled with wet soil. Attach it the same way you attached the corners.
Adding Landscape Fabric and Filling With Soil
Once the frame is level and square, lay landscape fabric across the bottom if you want to block weeds. Overlap the edges by a few inches and staple or pin it to the inside of the boards. This step is optional—many gardeners skip it and straightforward pull weeds as they appear—but it saves work in the first year.
Fill the bed with soil. Most gardeners use a mix of topsoil and compost in roughly equal parts, or they buy bagged garden soil. A 4-by-8-foot bed that is 10 inches tall holds about 26 cubic feet of soil, which is roughly 1 cubic yard. Calculate your bed's volume (length × width × depth in feet, then divide by 27 to get cubic yards) before you order, so you do not buy too much or too little.
Spread the soil evenly and water it lightly to help it settle. The soil will compact over the first few weeks, so you may need to add more later. Do not pack it down by stepping on it—loose soil drains better and is easier for roots to grow into.
Materials and Tools You Will Need
| Item | What It Does | Notes |
|---|---|---|
| Four boards (2×8 or 2×10) | Forms the walls of the bed | Cedar or composite last 10+ years; pine lasts 3–5 years |
| Corner brackets or 3-inch deck screws | Holds corners together | Brackets are faster; screws are cheaper |
| Drill or screwdriver | Drives screws | A cordless drill is faster but not required |
| Level | Ensures the bed is flat | A 2-foot level is easiest to handle |
| Landscape fabric (optional) | Blocks weeds from below | Staple it to the inside of the boards |
| Soil and compost | Growing medium for plants | Calculate volume before ordering |
Common Mistakes to Avoid
Do not use pressure-treated lumber from before 2004, which contains arsenic. Modern pressure-treated boards are safer, but cedar and composite are still better choices for vegetable gardens because they do not leach chemicals. Avoid creosote-treated railroad ties for the same reason.
Do not skip the level step. An unlevel bed will drain unevenly, leaving one end soggy and the other dry. This makes it hard to grow plants that need consistent moisture. Spend five minutes leveling and you will save weeks of watering problems.
Do not fill the bed with topsoil alone. Pure topsoil compacts and drains poorly. Mix it with compost or aged manure so water and roots can move through easily. A 50-50 mix of topsoil and compost is a good starting point.
Do not build the bed in a shaded spot hoping plants will adapt. Most vegetables need six to eight hours of sun. If your only option is partial shade, grow leafy greens and herbs instead of tomatoes or peppers.
When to Call a Professional
You do not need a professional to build a raised bed—it is a straightforward carpentry task. However, if your ground is very uneven, heavily compacted, or contaminated (for example, if the bed will sit over an old driveway), a landscaper can help you prepare the site properly.
If you want to build a very large bed or a permanent structure with a stone or composite border, a contractor can may support it is built to last and drains correctly. For most home gardeners, though, a straightforward wooden frame is the fastest and cheapest option.
Frequently Asked Questions
How deep should a raised bed be?
Eight to twelve inches is standard for most vegetables. Shallow-rooted crops like lettuce and herbs can grow in 6 inches, but tomatoes, peppers, and root vegetables need 10 to 12 inches. Deeper beds also drain better and warm up faster in spring.
Can I use treated lumber for a vegetable garden?
Modern pressure-treated lumber (made after 2004) is safe for vegetables because it no longer contains arsenic. However, cedar and composite boards are still preferred because they do not leach any chemicals and last longer. Avoid old treated lumber and railroad ties.
Do I have to use landscape fabric?
No. Landscape fabric blocks weeds from below, but many gardeners skip it and straightforward pull weeds as they appear. If your area has aggressive weeds or you are building over a lawn, fabric saves work in the first year. Staple it to the inside of the boards so it stays in place.
How much soil do I need?
Multiply length × width × depth (all in feet), then divide by 27 to get cubic yards. A 4-by-8-foot bed that is 10 inches deep needs about 1 cubic yard. Order from a landscape supplier or buy bagged soil from a garden center—bagged soil costs more but is easier to handle for small beds.
Can I build a raised bed on concrete?
Yes, but drainage will be poor because water cannot drain into the ground below. Drill holes in the landscape fabric or skip it entirely, and water more often. Alternatively, build the bed on soil or grass where water can drain naturally.