A raised bed with legs sits high enough to reach without bending and keeps soil off the ground

A raised garden bed with legs is a wooden or composite box mounted on a frame 2 to 3 feet above the ground. The legs elevate the soil, so you can plant and harvest without kneeling or stooping. The frame also keeps the bed away from tree roots and compacted soil underneath, and it makes it harder for slugs and some burrowing pests to reach your plants from below.

You can buy a pre-made elevated bed kit and assemble it in an afternoon, or you can build one from scratch using lumber and basic tools. Either way, the structure is straightforward: a rectangular box made of boards, supported by four legs bolted to the corners. The bed itself does not need a bottom — soil sits directly on the ground or on landscape fabric if you want a barrier.

Key Takeaways

  • A raised bed with legs typically stands 24 to 36 inches tall and uses 2-by-10 or 2-by-12 boards for the sides, with 4-by-4 posts cut to length for the legs.
  • You will need a drill, a saw, a level, and lag bolts or carriage bolts to fasten the legs to the corners of the box.
  • The bed does not need a bottom board — landscape fabric laid underneath stops weeds but lets water drain through.
  • Cedar and composite lumber last longer than untreated pine, but untreated wood is cheaper and safe for growing vegetables.
  • A bed 4 feet long by 2 feet wide by 2 feet tall holds about 16 cubic feet of soil and is straightforward to reach across from either side.

Choosing lumber and sizing your bed

The most common raised bed is built from four boards — two long sides and two short ends — bolted to four corner posts. A typical size is 4 feet long, 2 feet wide, and 24 inches tall, but you can adjust the dimensions to fit your space and reach. The longer the bed, the harder it is to reach the center without stepping in, so 4 feet is a practical limit if you want to tend plants from both sides.

For the sides, use 2-by-10 or 2-by-12 boards (these are actually 1.5 inches thick and 9.25 or 11.25 inches wide). For the legs, use 4-by-4 posts cut to the height you want the bed to stand. If you want the finished bed to be 24 inches tall, cut the posts about 26 inches long — the extra length gets bolted to the inside of the boards, so the boards sit on top of the posts and add their own thickness to the final height.

Cedar and composite lumber resist rot and last 10 to 15 years. Untreated pine lasts 5 to 8 years and costs less. Avoid pressure-treated wood made before 2004, which contains arsenic, but modern pressure-treated lumber is safe for vegetable gardens. Do not use railroad ties or old utility poles — they are often treated with creosote, which leaches into soil.

Assembling the box and attaching the legs

Lay the four boards on a flat surface in a rectangle and position the four corner posts at the inside corners. Each post should be flush with the top of the boards so that the boards rest on top of the posts. Drill pilot holes through the boards into the posts — use a drill bit slightly smaller than the diameter of your bolts so the bolts grip tightly.

Fasten each corner with two lag bolts (also called lag screws) or carriage bolts, one near the top and one near the bottom of the post. Lag bolts are easier for a beginner — you screw them in with a wrench. Carriage bolts require a nut and washer on the back side, which means you have to reach inside the bed to tighten them, but they are stronger. Use 3/8-inch bolts and tighten them firmly so the boards do not shift.

Once all four corners are bolted, place the bed on level ground and check it with a level in both directions. If one corner is higher than the others, you can shim under the legs with shingles or metal shims until the bed is level. A level bed drains evenly and looks neater.

Preparing the ground and adding landscape fabric

Clear the area where the bed will sit — remove grass, weeds, and large rocks. You do not need to dig out the soil underneath; the raised bed will sit on top of whatever is there. If the ground is very uneven, level it as much as you can by hand or with a shovel.

Lay landscape fabric on the ground inside the bed before you add soil. This blocks weeds from growing up into your bed and prevents tree roots from pushing through from below. Use a heavy-duty fabric rated for at least 5 years of outdoor use — cheap landscape cloth tears easily. Overlap the seams by 6 inches and staple the fabric to the inside of the boards so it does not shift when you water.

If you are building the bed on a patio or deck, you can skip the fabric and set the bed directly on the hard surface. Water will drain out the bottom, so make sure the surface slopes slightly or has a drain nearby.

Filling the bed with soil

Calculate how much soil you need by multiplying length × width × height in feet, then dividing by 27 to get cubic yards. A 4-by-2-by-2-foot bed holds about 0.6 cubic yards, or roughly 16 cubic feet. You can buy bagged soil or have a landscape supplier deliver bulk soil in a truck.

For a vegetable garden, use a mix of topsoil and compost — roughly 60 percent topsoil and 40 percent compost. This gives you good drainage and nutrients without being too dense. If you are planting perennials or shrubs, use a mix of topsoil, compost, and peat moss or coconut coir for better water retention.

Fill the bed to within 2 inches of the top. The soil will settle over the first few weeks, so you can add more later if needed. Water the soil thoroughly after filling so it settles and compacts slightly.

Protecting wood from rot and extending its life

Untreated wood lasts longer if you keep it dry. Do not let the bed sit in standing water, and make sure water drains away from the base of the posts. If you live in a very wet climate, you can explore a wood sealant to the outside of the boards — use a sealant rated for outdoor use and safe for vegetable gardens. Do not seal the inside of the bed, because the sealant can leach into the soil.

Cedar naturally resists rot because it contains oils that fungi dislike, but it still benefits from a coat of sealant every few years. Composite lumber does not rot but can fade and become brittle in direct sun, so a UV-protective sealant extends its life.

Check the posts and bolts every spring. If you see soft spots in the wood or rust on the bolts, tighten the bolts or replace them. If a post is rotting, you can cut it out and bolt in a new one — you do not have to rebuild the whole bed.

Alternatives if you do not want to build from scratch

Pre-made raised bed kits come with all the boards and hardware you need. You assemble them by bolting the corners together — no cutting or drilling required. Kits cost more than buying lumber separately, but they save time and the pieces fit together precisely. Most kits come in standard sizes like 4-by-2 or 3-by-3 feet.

Metal-frame raised beds use aluminum or steel instead of wood. They do not rot and last 20+ years, but they can get hot in direct sun and are more expensive upfront. Composite beds made from recycled plastic and wood fibers split and crack less than wood, but they are also pricier.

If you want a very tall bed for accessibility — say, 36 inches or higher — you can stack two standard beds on top of each other, bolting them together at the corners. This works well for people with mobility issues who cannot bend down to reach a standard-height bed.

Frequently Asked Questions

Do I need a bottom board on my raised bed?

No. A bottom board traps water and causes the posts to rot faster. Landscape fabric underneath stops weeds and roots but lets water drain through. If you want to keep burrowing animals out, use hardware cloth (a metal mesh) instead of fabric, but make sure water can still drain.

Can I use treated lumber for vegetables?

Yes. Modern pressure-treated lumber (made after 2004) is safe for vegetable gardens. It contains copper compounds, not arsenic. Avoid old treated wood from before 2004 and railroad ties, which contain creosote.

How deep does a raised bed need to be for vegetables?

Most vegetables need 12 to 18 inches of soil. Shallow-rooted crops like lettuce and spinach do fine in 12 inches. Root vegetables like carrots and beets need 18 inches or more. A 24-inch-tall bed gives you room for most vegetables and still lets you reach the bottom easily.

What if the ground is not level?

You can shim under the legs with shingles or metal shims until the bed is level, or you can dig out the high spots and fill in the low spots. A level bed drains evenly and is easier to work in. If the slope is steep, you may need to build the bed into a hillside or use a retaining wall on the downhill side.

How often do I need to replace the boards?

Untreated pine lasts 5 to 8 years. Cedar lasts 10 to 15 years. Composite and metal last 20+ years. You can replace just the boards without rebuilding the legs — unbolt the old boards and bolt new ones to the same posts.