A raised bed with legs sits high enough to reach without bending and keeps soil off the ground
A raised bed with legs is a wooden or composite box built on a frame that lifts the soil 24 to 36 inches off the ground. The legs do two things: they let you garden without kneeling or bending, and they keep the soil separated from whatever is underneath—concrete, compacted earth, or poor native soil. You build it by constructing a rectangular box from boards, then attaching four legs underneath, then filling it with soil.
The whole project takes a weekend if you have basic tools and materials on hand. You do not need to be a carpenter. The structure is straightforward: four sides, four legs, fastened together with screws. The most common mistake is using wood that rots quickly or legs that are too thin to hold the weight of wet soil.
Key Takeaways
- Cedar, composite, or untreated pine boards last longer than pressure-treated wood, which can leach chemicals into soil over time.
- Legs should be at least 4 inches by 4 inches in cross-section and set into the ground 6 to 12 inches deep so the bed does not shift or tip.
- Screw the box together from the outside, then attach legs to the inside corners before filling, because the weight of soil makes assembly harder afterward.
- A bed 4 feet by 8 feet by 12 inches deep holds about 32 cubic feet of soil and costs $150 to $300 in materials depending on wood choice.
Choose wood that will not rot in a year or two
The wood you pick determines how long the bed lasts. Cedar and redwood naturally resist rot and last 10 to 15 years. Composite boards made from wood fiber and plastic last 15 to 20 years but cost more upfront—usually $3 to $6 per linear foot versus $1 to $3 for cedar. Untreated pine is cheap but rots in 3 to 5 years, especially at the corners where water pools. Avoid pressure-treated wood if you are growing vegetables, because the chemicals used to preserve it can leach into the soil.
For a standard 4-by-8-foot bed that is 12 inches tall, you need two 8-foot boards and two 4-foot boards. Buy them an inch or two longer than you need—you will trim them to exact length as you assemble. If your local supplier does not stock cedar, ask whether they can special-order it; the wait is usually one to two weeks.
Cut and assemble the four-sided box
Lay the four boards on a flat surface in a rectangle. Cut the ends at 45-degree angles if you want the corners to look finished, or leave them square—both work structurally. Drill pilot holes (small starter holes) through the ends of the two longer boards into the ends of the two shorter boards. This prevents the wood from splitting when you drive screws in.
Use 3-inch exterior-grade screws—two or three per corner. Drive them from the outside of the box so the heads are visible but the fasteners are pulling the corners tight. Do not use nails; screws hold better and let you adjust the corners if they are not square. Once all four corners are fastened, lay the box on a flat surface and check that all four corners touch the ground. If one corner is high, the box is twisted; loosen the screws at that corner, shift the boards slightly, and retighten.
Build and attach legs that go into the ground
The legs are what keep the bed from sinking or tipping as the soil settles and gets wet. Cut four pieces of 4-by-4 lumber to 24 inches long—this gives you 12 inches above ground and 12 inches to drive into the earth. If your soil is very hard or you want the bed higher, cut them longer; if you want it lower, cut them shorter, but never shorter than 18 inches total.
Position each leg at an inside corner of the box and fasten it with three or four 3-inch screws driven horizontally through the side boards into the leg. Drill pilot holes first so the wood does not split. The legs should be flush with the inside edges of the box, not sticking out. Once all four legs are attached, flip the entire assembly upside down and check that all four leg ends are even. If one is shorter, the bed will rock; trim the others to match or add a shim (a thin wedge) under the short one.
Set the bed in place and level it
Move the bed to its final location. Clear away grass and weeds from the footprint—you do not need to dig, but remove anything that will rot under the bed. Set the bed down and use a 4-foot level to check that the top edges are level in both directions. If the ground slopes, dig out the high side slightly or add soil under the low side until the bed is level. A bed that is not level will have shallow soil on one end and deep soil on the other, and water will pool in the low corner.
Once the bed is level, drive the legs into the ground by tapping them with a mallet or small sledgehammer. Aim for 6 to 12 inches of leg buried in the soil. This anchors the bed so it does not shift when you walk on the edges or when frost heaves the ground in winter. If the soil is very hard, soak the area around each leg with water the day before to soften it.
Fill with soil and let it settle
A 4-by-8-foot bed that is 12 inches deep holds about 32 cubic feet of soil. You can buy this as bagged garden soil (about 40 bags of 0.75 cubic feet each) or as bulk soil delivered by a landscape supplier. Bulk is cheaper if you are filling more than one bed. Fill the bed to the top, water it thoroughly, and let it sit for a few days. The soil will settle 1 to 2 inches as it compacts and the air pockets collapse. Top it off with more soil before you plant.
Do not use pure compost or pure peat moss—they hold too much water and compress over time. A mix of topsoil, compost, and perlite or coarse sand drains better and lasts longer. If you are unsure what to buy, ask the soil supplier what they recommend for raised beds.
Maintain the bed so it lasts
Check the corners and leg fasteners once a year, usually in spring. Tighten any screws that have loosened. If you see rot starting at the base of a board, you can cut out the rotted section and splice in a new piece, or replace the whole board—cedar boards are not expensive. If a leg is rotting, replace it before it fails completely.
In cold climates, frost can heave the bed upward in winter. After the first hard freeze, check that the legs are still driven into the ground as far as they were in fall. If the bed has lifted, drive the legs back down. This is normal and not a sign of a problem.
Frequently Asked Questions
Can I use pressure-treated wood for a vegetable garden?
Modern pressure-treated wood is safer than older versions, but most gardeners avoid it for vegetables because the preservatives can leach into soil over decades. Cedar, composite, or untreated pine are better choices. If you already have a pressure-treated bed, you can line the inside with landscape fabric to reduce contact between soil and wood.
How deep should the bed be?
Most vegetables need 8 to 12 inches of soil. Shallow-rooted plants like lettuce and spinach do fine at 8 inches; deeper-rooted plants like tomatoes and carrots need 12 inches or more. A 12-inch bed is a good middle ground. If you want to grow root vegetables like parsnips, go 18 inches deep.
Do I need to put landscape fabric on the bottom?
Landscape fabric is optional. It keeps weeds from growing up from the ground below but also slows drainage. If your ground is very weedy or you are building on concrete, use it. If you are on decent soil, you can skip it—the soil in the bed will stay separate from what is underneath.
What if the ground is too hard to drive the legs in?
Soak the soil around each leg with water the day before. If it is still hard, you can drill pilot holes with a power drill and a long bit, then drive the legs into those holes. Alternatively, dig a small hole at each corner, set the leg in, and backfill with soil, but this is less stable than driving the legs in.
Can I build a raised bed with legs on a deck or patio?
Yes, but the legs need to rest on something solid. On a deck, make sure the deck can support the weight—a full 4-by-8 bed weighs 800 to 1,200 pounds. On concrete, the legs will not sink in, so you can use shorter legs or even no legs at all. Make sure water can drain away from the patio so it does not pool underneath.