Build a raised bed by stacking untreated wood boards, securing the corners, and filling with soil

A raised garden bed is a wooden or composite box you fill with soil and plant into. The simplest version uses four boards screwed or nailed together at the corners, sitting directly on the ground. You do not need concrete, a foundation, or special tools—a drill, a saw, and a level are enough to build one that will last several seasons. Most home gardeners build beds 4 feet long, 2 feet wide, and 10 to 12 inches tall, though you can adjust these dimensions to fit your space and what you want to grow.

The whole project takes 2 to 3 hours from start to finish, including filling with soil. You can plant into the bed the same day you build it, though waiting a week lets the soil settle and compost begin breaking down.

Key Takeaways

  • Untreated cedar or composite boards last longer than pine and do not leach chemicals into soil the way treated wood can.
  • A 4-by-2-foot bed 10 inches tall requires about 16 cubic feet of soil, which costs between $20 and $50 depending on soil quality and where you live.
  • Screwing boards together at the corners is stronger and faster than nailing, and corner brackets add stability if you are building a tall or large bed.
  • A level bed drains evenly and prevents water from pooling; check it before you fill it with soil.
  • You can build a raised bed in an afternoon and plant into it the same day.

Choose your wood and cut it to length

Untreated cedar is the most common choice because it resists rot for 5 to 10 years without chemicals. Composite boards (wood fiber mixed with plastic) last 15 to 20 years but cost more upfront. Avoid pressure-treated wood—the chemicals used to preserve it can leach into soil over time, especially if you are growing vegetables. Pine is cheaper but rots in 3 to 5 years.

For a standard 4-by-2-foot bed, you need two boards 4 feet long and two boards 2 feet long. If you are buying boards from a home improvement store, they often come pre-cut to 8 feet or 10 feet. Ask the store to cut them for you, or use a circular saw or hand saw at home. Boards are usually 2 inches thick and 10 or 12 inches tall; a 10-inch board gives you a bed that is roughly 8 inches deep after accounting for the thickness of the wood.

Assemble the frame on level ground

Lay the four boards on the ground in a rectangle, with the short boards inside the long boards at the corners. This overlap makes the frame stronger. Drill two holes through each long board into the end of each short board, spacing the holes about 1 inch from the top and bottom of the board. Use a drill bit slightly smaller than your screws so the wood does not split.

Drive 3-inch exterior-grade screws through the holes. Two screws per corner is the minimum; three or four per corner makes the frame more rigid, especially if you are building a bed taller than 12 inches or longer than 6 feet. Tighten each screw firmly but do not over-tighten—you will strip the wood or bend the screw.

Once the frame is screwed together, place it where you want it to sit. Use a level to check that the ground inside the frame is roughly flat. If one corner is higher than the others, dig out soil from the high side or add soil to the low side until the frame sits level. A bed that is not level will drain unevenly and water will pool in the low corner.

Reinforce corners if you are building tall or wide

If your bed is taller than 12 inches or longer than 6 feet, the weight of the soil will push the boards outward over time. Corner brackets (L-shaped metal or plastic pieces) prevent this. Attach them on the inside of the frame, one on each corner, using the screws that come with the bracket.

You can also build a bed without corner brackets by using thicker boards (2-by-12 instead of 2-by-10) or by making the bed smaller. A 3-by-3-foot bed with 10-inch boards rarely needs bracing. If you are unsure, add the brackets—they cost $5 to $15 per corner and take 5 minutes to install.

Fill the bed with soil and let it settle

Before you fill the bed, lay landscape fabric on the bottom if you want to prevent weeds from growing up from the ground below. This is optional—many gardeners skip it and pull weeds as they appear. If you use fabric, overlap the seams by 6 inches and cut an X in the fabric at each corner so water can drain through.

Fill the bed with a mix of topsoil and compost. A 50-50 blend is standard, though you can adjust the ratio depending on what you are growing. Vegetables prefer richer soil, so add more compost. Herbs and ornamentals do fine with more topsoil. A 4-by-2-foot bed 10 inches tall holds about 16 cubic feet of soil. Soil is sold by the cubic yard (27 cubic feet), so you will need about 0.6 cubic yards, or roughly half a cubic yard. Most garden centers sell bags of topsoil and compost if you do not want to buy a full cubic yard.

After you fill the bed, water it thoroughly. The soil will settle over the next few days, and you may need to add more soil to bring it back to the top of the frame. Wait a week before planting if you can—this gives the soil time to settle and the compost to begin breaking down.

Position your bed for sunlight and water access

Most vegetables need 6 to 8 hours of direct sun per day. Herbs need 4 to 6 hours. Leafy greens tolerate partial shade. Before you build, observe your yard throughout the day and note where the sun hits. A bed in the wrong spot is hard to move once it is full of soil.

Position the bed where you can reach the center easily—a 4-foot-wide bed is the maximum most gardeners can reach across comfortably. If you are building a longer bed, make it narrower (2 feet instead of 3) so you can reach plants in the middle without stepping on the soil. Leave at least 2 feet of space around the bed for a path, a wheelbarrow, or a hose.

Common mistakes to avoid

Building on unlevel ground. Even a 1-inch difference in height will cause water to pool. Spend 10 minutes leveling the ground before you fill the bed.

Using treated wood. Pressure-treated lumber sold before 2004 contained arsenic. Modern treated wood is safer but still not ideal for vegetable gardens. Stick with cedar or composite.

Filling with only compost. Pure compost drains too fast and compacts over time. Mix it with topsoil for better water retention and structure.

Placing the bed in shade. A bed that gets 3 hours of sun will produce less than one in full sun. Check your yard's light before you commit to a location.

Making the bed too wide. A 3-foot-wide bed is harder to reach across than a 2-foot bed. If you want a larger growing area, build two beds instead of one wide one.

Frequently Asked Questions

How deep does a raised bed need to be?

Most vegetables need 8 to 12 inches of soil. Shallow-rooted crops like lettuce and herbs do fine in 6 inches. Root vegetables like carrots and parsnips need 12 inches or more. A 10-inch bed is a good middle ground for a mixed vegetable garden.

Can I build a raised bed on top of grass?

Yes, but the grass underneath will eventually rot and create air pockets in the soil. Mow the grass short, lay landscape fabric over it, and build the bed on top. The fabric prevents grass from growing up into the bed and slows decomposition, which keeps the soil level longer.

What size raised bed should I start with?

A 4-by-2-foot bed is a good first size—large enough to grow a variety of plants but small enough to manage without feeling overwhelming. It holds about 16 cubic feet of soil and costs $30 to $80 in materials, depending on wood choice.

Do I need to add fertilizer to a new raised bed?

A 50-50 mix of topsoil and compost usually has enough nutrients for the first season. After that, add 1 to 2 inches of compost each spring to replenish nutrients as plants use them up.

How long does it take to build a raised bed?

Cutting boards, assembling the frame, and leveling the ground takes 1 to 2 hours. Filling it with soil takes another 30 minutes to an hour, depending on how far you have to carry the soil. You can plant the same day you fill it.