The cheapest way to build raised beds with legs

The cheapest raised beds with legs use untreated wood boards, concrete blocks, or a combination of both. A 4-by-8-foot bed with 12-inch legs costs $30 to $50 in materials if you use pine boards and straightforward wooden posts, or $20 to $35 if you stack concrete blocks as the frame and add wooden legs only at the corners. The trade-off is that pine rots in 3 to 5 years outdoors, while concrete blocks last indefinitely but weigh more and look industrial.

The fastest budget option is stacking concrete blocks without any wood at all — you get when ready legs and a frame for $15 to $25, depending on block count. If you want wood for appearance or easier planting, buy untreated pine 2-by-10 or 2-by-12 boards from a lumber yard (not a big-box store, which charges more) and attach them to four wooden posts set into the ground or concrete footings.

Key Takeaways

  • Untreated pine boards cost half as much as cedar or composite materials and work fine for 3 to 5 years before rotting, making them the cheapest wood choice.
  • Stacking concrete blocks requires no fasteners or tools and creates a sturdy frame with built-in legs for $15 to $25 per bed.
  • Wooden corner posts set into the ground or concrete footings cost less than building a full wooden frame and prevent the bed from racking (twisting out of square).
  • Untreated wood lasts longer if you line the interior with landscape fabric or cardboard to separate soil from wood, slowing rot by one to two years.

Untreated pine boards and corner posts

Buy untreated 2-by-10 or 2-by-12 pine boards and four 4-by-4 posts cut to your desired height. For a 12-inch-tall bed, buy 4-by-4 posts 18 to 24 inches long — the extra length goes into the ground or into concrete footings for stability. A 4-by-8-foot bed needs four boards (two 8-foot lengths and two 4-foot lengths) and four posts.

Attach the boards to the posts using 3-inch exterior wood screws (not nails, which pull loose). Drill pilot holes first to prevent splitting. Set the posts into the ground at least 6 inches deep, or pour a small concrete footing around each post if your soil is sandy or loose. This method costs $30 to $45 for a 4-by-8 bed and takes 2 to 3 hours to build.

Untreated pine will develop gray weathering within a year and begin rotting after 3 to 5 years depending on rainfall and soil contact. You can extend its life by lining the interior with landscape fabric or cardboard before filling with soil — this slows water absorption into the wood. Do not use treated wood with arsenic (older stock) or pressure-treated wood with copper compounds if you are growing vegetables, as the chemicals can leach into soil.

Stacked concrete blocks

Stack standard 8-by-8-by-16-inch concrete blocks to form the frame, using no mortar. Lay the first course flat, then stack a second course on top, offsetting the joints like brickwork. For a 4-by-8-foot bed 12 inches tall, you need 12 blocks (three per long side, two per short side, plus one extra for corners). Cost is typically $2 to $3 per block, so $24 to $36 total.

Concrete blocks are heavy — a single block weighs 40 to 50 pounds — so this method works best if you are building the bed in place rather than moving it. The blocks themselves act as legs, sitting directly on the ground. No fasteners are needed. The interior edges are rough, so line the bed with landscape fabric to prevent soil from falling through the gaps.

Concrete blocks last 20+ years and do not rot. The downside is appearance — they look utilitarian — and they absorb and retain heat, which can dry soil faster in summer. If you want a hybrid approach, use concrete blocks for the frame and attach wooden corner posts on top for a finished look.

Hybrid: concrete blocks with wooden posts

Stack concrete blocks two high (16 inches) to form the frame, then attach 4-by-4 wooden posts to the top inside corners using lag bolts or concrete anchors. This gives you the durability of concrete with the appearance of wood. The posts can extend above the blocks to create a taller bed (24 inches total) without adding more blocks.

Drill holes through the posts and into the blocks, then use 3/8-inch lag bolts with washers and nuts, or concrete screws rated for masonry. This method costs $35 to $50 for a 4-by-8 bed and takes 3 to 4 hours. The wooden posts will still rot eventually, but they are replaceable — you can remove and swap them out without rebuilding the entire frame.

Avoiding common mistakes

Do not skip the corner posts or rely on board-to-board joints alone. A frame made only of boards bolted at the corners will rack (twist out of square) within a season as the wood settles and soil weight pushes outward. Posts prevent this by anchoring the corners to the ground.

Do not use treated wood with copper-based preservatives (CCA or ACQ) for vegetable beds. Older treated wood contains arsenic; newer treated wood contains copper compounds that can leach into soil. Untreated wood is safer and cheaper for food gardens. If you want durability, use cedar or composite materials, but expect to pay $60 to $100 per bed.

Do not fill the bed when ready after building. Let wooden frames settle for a week, especially if you used ground-set posts. Soil weight will compress the wood slightly, and you want this to happen before you plant. Check that the frame is still square using a tape measure across the diagonals — both measurements should be equal.

Tools and fasteners you will need

For wooden construction, buy 3-inch exterior wood screws (about $8 for a box of 50), a power drill with a screwdriver bit, and a 1/4-inch drill bit for pilot holes. A circular saw or hand saw helps cut boards to length, but most lumber yards will cut them for free or a small fee. A level ensures the bed sits flat. Total tool cost is $0 if you already own a drill, or $40 to $60 if you need to buy one.

For concrete block construction, you need only a level and a tape measure. If you are using lag bolts to attach wooden posts to blocks, add a 3/8-inch drill bit rated for masonry (about $5) and lag bolts with washers and nuts (about $15 for a set of four). A concrete anchor kit is an alternative and costs about $10.

Filling and maintaining your bed

Fill the bed with a mix of topsoil and compost — roughly 60 percent topsoil and 40 percent compost by volume. For a 4-by-8-foot bed 12 inches deep, you need about 32 cubic feet of soil, or roughly 1.2 cubic yards. Bulk soil costs $25 to $40 per cubic yard delivered, so budget $35 to $50 for fill. This brings your total project cost to $65 to $100 for a complete bed ready to plant.

Wooden beds need annual maintenance. Check the posts and boards each spring for rot, especially where wood meets soil. If you see soft spots, the wood is breaking down. Untreated pine typically lasts 3 to 5 years before replacement becomes necessary. Concrete blocks need no maintenance beyond occasional cleaning.

Frequently Asked Questions

Can I use pallets to build a raised bed with legs?

Pallets are free or cheap, but most are treated with pesticides or fungicides for shipping. If you use them, choose pallets marked "HT" (heat-treated only) rather than "MB" (methyl bromide). Even heat-treated pallets are often dirty and splintered. Untreated pine boards cost only $5 to $10 more and are cleaner and safer for food gardens.

How deep should the legs be?

Posts should go at least 6 inches into the ground for stability. For a 12-inch-tall bed, buy 18 to 24-inch posts so you have enough length both above and below ground. If your soil is sandy or loose, go 8 to 10 inches deep or use concrete footings instead of ground-set posts.

Will untreated wood rot faster if I line it with plastic?

Landscape fabric or cardboard slows rot by keeping soil moisture off the wood, but plastic sheeting can trap moisture and speed decay. Use breathable landscape fabric, not plastic. Cardboard works too and is free if you save boxes from deliveries.

Can I build a raised bed on a concrete patio?

Yes, but the wood will rot faster because water cannot drain away. Use concrete blocks instead, or build a wooden frame and set it on concrete blocks rather than directly on the patio. This creates air space underneath and lets water drain.

What size bed should I build?

A 4-by-8-foot bed is standard and costs $30 to $50 in materials. A 4-by-4-foot bed costs $20 to $35. Avoid beds wider than 4 feet — you will not be able to reach the center from either side without stepping into the bed, which compacts soil. Length does not matter as much, so build as long as your space allows.