How to Build a Simple Raised Garden Bed

Preflight — pick the site, decide dimensions, and gather materials and tools.

6+ hours of sun · level, root-free ground · dimensions chosen · materials gathered.

Picking the right site and deciding your dimensions before you cut a single board prevents the two most common regrets: a bed that struggles in shade or root competition, and a frame too wide to reach the center of.

1. Choose a site with at least 6 hours of direct sun, reasonably level ground, and no large tree or shrub roots nearby.
2. Decide your dimensions — a 4x8-foot bed at least 12 inches deep is a solid default, kept to 4 feet or less in width so you can reach the center from either side.
3. Gather untreated cedar or fir boards, corner posts, exterior screws, a drill, saw, tape measure, level, cardboard or landscape fabric, and soil-mix ingredients.

The site is chosen, dimensions are decided, and all lumber, tools, and soil-mix materials are on hand.

Site slopes noticeably or you're unsure the ground is level? See Unlevel site.

Clear and prep the site footprint.

Remove grass, sod, weeds, and debris from the exact bed footprint.

Grass and weeds left underneath will push up through any gaps and compete with your vegetables, and it's far easier to clear the ground now than after the frame and soil are in place.

1. Mark the bed's footprint with stakes and string or a tape measure.
2. Cut and remove sod or grass with a flat shovel or edger, or plan to smother it with cardboard in a later step.
3. Rake the area to remove rocks, roots, and other debris.

The marked footprint is clear of grass, sod, rocks, and debris, or ready to be smothered with cardboard.

Measure and mark your cut list.

Mark every board and post with its exact cut length before cutting anything.

Marking every piece first prevents a common, expensive mistake — cutting a board short because you measured while cutting instead of before.

1. Decide the finished outside dimensions (e.g., 4x8 feet) and depth (12 inches is a good default).
2. Mark two long boards and two short boards, subtracting board thickness so the outside width comes out correct.
3. Mark four corner posts at your chosen depth, such as 12 inches.

Every board and post has a clear pencil mark showing its exact cut length, matching your chosen dimensions.

Cut the boards and corner posts to length.

Cut each piece exactly on its mark with a circular saw or handsaw.

Cutting exactly on the marks now is what makes the frame's diagonals match later — even a half-inch of drift on one board throws the whole rectangle out of square.

1. Clamp each board securely before cutting.
2. Cut on the outside of your pencil line so the piece doesn't come out short.
3. Cut all four corner posts to the same length so the frame sits level on all four corners.

All boards and posts are cut and match the lengths from your cut list.

Pre-drill pilot holes near each board end.

Drill two pilot holes near every end that will meet a corner post.

Cedar and fir end grain splits easily under a screw driven straight in, and a split board loses most of its holding strength right at the corner where you need it most.

1. Use a drill bit slightly smaller than your screw's shank.
2. Drill two pilot holes near each end of every long and short board.
3. Keep holes about 3/4 inch from the board edge to avoid splitting.

Two pilot holes are drilled near each end of every board before any screw is driven.

Assemble the first long side onto two corner posts.

Screw one long board to a corner post at each end, flush top and bottom.

Building each side flat on the ground first is easier and more accurate than trying to hold three loose boards and a post together in midair.

1. Lay one long board flat and stand a corner post at each end, flush with the top edge and one face.
2. Drive screws through the pre-drilled holes into the post at each end.
3. Check that each post sits flush with both the top edge and the outside face of the board.

One long board is solidly screwed to a corner post at each end, both posts flush with the board's top edge.

Assemble the second long side the same way.

Repeat the same post-and-board assembly for the other long side.

Building both long sides the same way keeps the finished frame symmetrical, so the short end boards will line up evenly when you close the rectangle.

1. Lay the second long board flat and attach a corner post at each end the same way as the first.
2. Match the post orientation to the first side so the frame will close correctly.
3. Set both completed long sides aside, ready to stand up.

The second long board is solidly attached to its own two corner posts, matching the first side.

Stand the long sides up and attach the short ends.

Stand both long sides on edge and screw the short boards between the posts.

This is the step that actually turns two separate side panels into one connected rectangle, so every screw here carries real structural weight.

1. Stand both long sides up on their edge, posts facing inward, roughly 4 feet apart.
2. Fit one short board between the posts at one end, flush with the top, and drive screws through the pre-drilled holes.
3. Repeat at the other end with the second short board.

All four corners are screwed together and the frame stands on its own as one connected rectangle.

Frame feels loose, twisted, or won't sit flat? See Warped frame.

Check the frame for square by measuring both diagonals.

Measure corner-to-corner in both directions and compare.

Equal diagonals are the only reliable way to confirm a rectangle is actually square — eyeballing the corners can look fine while the frame is really a parallelogram.

1. Measure from one corner diagonally to the opposite corner.
2. Measure the other diagonal the same way.
3. Compare the two numbers — they should match within about 1/4 inch.

Both diagonal measurements match within about 1/4 inch.

Diagonals don't match, or the frame feels twisted or bowed? See Warped frame.

Move the frame to its final spot and check level.

Set the frame in place and check a level on all four sides.

A frame that's level keeps water spread evenly across the soil instead of pooling against one wall, which is what makes that wall rot faster than the rest.

1. Carry or slide the frame onto its prepared site.
2. Place a carpenter's level along the front, back, and both end boards.
3. Note which side, if any, reads low.

A level reads level on all four sides, or you know exactly which side needs adjusting.

Site slopes, or the frame rocks/shows a gap underneath on one side? See Unlevel site.

Line the bottom with cardboard or landscape fabric.

Lay overlapping cardboard, tape and staples removed, or landscape fabric across the bottom.

A solid weed barrier now blocks existing grass and weeds from growing up into your new soil, saving you from pulling the same weeds all summer.

1. Lay flattened cardboard so pieces overlap by several inches, or roll out landscape fabric to cover the footprint.
2. Remove all tape and packing labels from cardboard — they don't decompose.
3. Let the edges run slightly up the inside walls or a few inches past the frame.

The entire bottom footprint is covered with no gaps, and all tape or staples are removed from any cardboard used.

Fill the bed in layers, watering between each layer.

Add soil mix a few inches at a time, watering lightly between layers.

Filling all at once traps dry air pockets that collapse later, while watering between layers settles the mix now instead of leaving you with sudden sinkholes after planting.

1. Mix or layer topsoil, compost, and a smaller amount of perlite or vermiculite, roughly 60/30/10.
2. Add the mix in layers about 4 to 6 inches deep at a time.
3. Water each layer lightly before adding the next.

The bed is filled to near the top in even layers, with each layer dampened before the next was added.

Water the entire bed thoroughly once full.

Soak the whole surface evenly with a hose or watering can.

A full, even watering now reveals any dry spots or fast-draining corners while you can still easily add more soil to fix them.

1. Water slowly across the entire surface, not just the center.
2. Watch for water running off the top instead of soaking in, which means you're going too fast.
3. Check corners and edges, which often dry out or drain faster than the middle.

Water soaks in evenly across the whole surface without pooling on top or running off the sides.

Top off settled soil and leave a rim gap.

Refill any low spots and stop about 1 inch below the top edge.

Leaving a small gap below the rim keeps mulch and soil from washing over the edge during heavy rain, and it's easier to add a little more soil now than to dig out overfilled soil later.

1. Check the surface for low spots, especially near corners and edges.
2. Add more soil mix to bring the surface level.
3. Stop filling about 1 inch below the top edge of the frame.

Soil sits roughly 1 inch below the top edge across the whole surface, with no visible low spots.

Soil keeps sinking or a sinkhole reopens after this? See Soil settling.

Do a final check before planting.

Confirm the frame is level, square, and filled evenly before you plant.

A quick final check catches anything you'd rather fix now, before roots are in the ground, instead of after.

1. Recheck the level on all four sides.
2. Look across the soil surface for any remaining low spots or gaps at the edges.
3. Confirm the frame still feels solid at each corner with no rocking.

The bed reads level, the frame feels solid at every corner, and the soil surface is even and ready to plant.