Build
How to Build a Raised Garden Bed
To build a raised garden bed, screw two rows of 2x6 boards to short 4x4 posts at each corner, check it for square, level it, and fill it. A 4x8 bed 11 inches tall takes six boards and an afternoon.
| Item | Detail |
|---|---|
| Finished size | 4 ft x 8 ft outside, 11 in tall |
| Lumber | Six 2x6 x 8 ft boards, one 4x4 x 6 or 8 ft |
| Fasteners | About 40 exterior screws, 3 in long |
| Time | 2 to 4 hours, plus leveling and filling |
| Soil to fill | About 26 cu ft (0.97 cu yd) |
| Lifespan | Pine 3–7 years; cedar 10–15+; modern treated 10+ |
Pick the spot
Choose your sunniest patch. Most vegetables want 6 to 8 hours of direct sun; leafy greens and herbs get by on 4 to 6. Stay near a hose, since raised beds dry out faster than ground beds.
Pick ground that is close to level and drains after rain, away from tree roots, which move into rich soil within a season or two. Leave at least 18 to 24 in on every side you need to reach, or about 3 ft where a wheelbarrow has to pass. If you are placing several beds, sketch the plot first with our layout and spacing guide.
Materials and tools
Cedar, redwood and cypress resist rot for 10 to 15 years or more, untreated pine is cheapest but lasts about 3 to 7, and modern copper-treated lumber is a long-lived middle ground. See the best wood for raised garden beds for a full comparison. Never build with old railroad ties or salvaged lumber that may carry the old arsenic-based treatment.
Tools you need:
- Circular or miter saw and a speed square
- Drill-driver with a 1/8-in pilot bit
- Tape measure, pencil and a 4-ft level
- Flat shovel, plus a staple gun if you add hardware cloth
- Safety glasses, hearing protection and gloves
Use coated deck screws or stainless steel. Interior screws rust and nails work loose.
Cut list for a 4x8 bed
This bed stacks two rows of 2x6 boards. Each row adds 5 1/2 in, the true width of a 2x6, for 11 in total. The long sides use full 8-ft boards with no cuts. The ends fit between the long sides, so each one is 48 in minus two board thicknesses: 45 in. Posts sit in the inside corners, plus one mid-side post on each long wall to stop bowing.
| Part | Stock | Cut length | Quantity |
|---|---|---|---|
| Long sides | 2x6 x 8 ft | 96 in (no cut) | 4 boards |
| End pieces | 2x6 x 8 ft | 45 in | 4 pieces from 2 boards |
| Corner posts | 4x4 | 11 in | 4 |
| Mid-side posts | 4x4 | 11 in | 2 |
| Screws | 3-in exterior | — | About 40 |
Each 8-ft board yields two 45-in end pieces. Six 11-in posts use 66 in of 4x4, so a 6-ft post is enough. If you want a deeper bed, the raised garden bed plans page covers a three-row version and other shapes.
Step-by-step assembly
- Cut the four 45-in end pieces and the six 11-in posts. Sand or knock off any splinters on the cut ends.
- Build each end first. Lay two 45-in pieces on edge, one above the other, on a flat surface. Set a post at each end, flush with the board ends and the top edge.
- Pre-drill and drive two screws through each board into each post, keeping screws at least 3/4 in from the board end so the wood does not split.
- Stand the two finished ends up, 8 ft apart, with the posts facing inward.
- Hold a long board against the ends so it covers the end grain of the short boards. Screw it into both corner posts, two screws per board end. Add the second long board above it, then repeat on the other side.
- Fit a post at the center of each long side, 48 in from either end, and screw both boards to it.
- Measure corner to corner both ways. When the two diagonals match (about 107 5/16 in), the bed is square. Push on the long corners until they do.
That is 16 board ends at the corners and 4 board crossings at the middle posts, two screws each, for 40 screws.
Level, line and protect
Set the frame in place. Shave off high spots so all four corners sit firm, checking each side with the level. On a gentle slope, dig the uphill side down rather than propping the low side on rocks; a gap under one corner lets soil wash out.
Most beds need no solid bottom; cardboard smothers grass and breaks down in a season. If gophers or voles live nearby, staple 1/2-in hardware cloth across the underside of the frame before setting it in place. Our guide to what to put in the bottom of a raised bed covers each option.
If you used treated lumber and prefer extra caution, line only the inside walls with heavy plastic sheeting, leaving the bottom open for drainage. Skip rocks or gravel in the base. They do not improve drainage.
Fill and plant
At 11 in deep, this frame holds about 26 cu ft once you subtract the posts, a little under 1 cu yd. Order a full yard and keep the extra for topping up: new soil sinks 2 to 3 in during its first season.
A reliable fill is about 60% screened topsoil, 30% compost and 10% pine bark fines, perlite or pumice. Water it well and let it settle for a day before planting. For bagged and bulk options, see our raised garden bed soil mix ratios.
Plant, water deeply and spread 2 to 3 in of straw or shredded leaves as mulch. Add 1 to 2 in of compost each spring.
How to choose
Choose pine if
You want the smallest outlay and accept rebuilding in about 3 to 7 years.
Choose cedar if
You want a frame that lasts 10 to 15 years or more without chemical treatment.
Add hardware cloth if
Gophers, moles or voles are active in your yard. It is far harder to add later.
Related guides
- Raised garden bed plans and designs
- Best wood for raised garden beds
- What to put in the bottom of a raised bed
- The best soil mix for raised garden beds
- How to fill a raised garden bed cheaply
Are corner posts necessary, or can the boards be screwed together?
Screws driven into end grain hold for a season, then loosen. A 4x4 post in each corner gives the screws solid wood and keeps both rows in line. Metal corner brackets are another option.
Should the posts go into the ground?
They can. Cut them 6 in longer and bury the extra for a bed that will not shift, which helps on soft or sloped ground. On firm, level soil, flush posts are fine.
How long does it take to build a 4x8 bed?
Once the boards are cut, assembly takes about an hour. Leveling the site and filling usually take longer than the frame.