What you need to build a raised bed and get it growing

A raised bed is a wooden or composite box you fill with soil and plant directly into. To build one, you need lumber (usually 2-by-10 or 2-by-12 boards), corner brackets or wood screws, a drill or screwdriver, a level, and soil. Most people finish in an afternoon. The bed itself costs between $50 and $200 depending on size and material; soil and amendments add another $30 to $100.

The real work is not assembly—it is choosing the location, preparing the ground underneath, and filling it with the right soil mix. A bed in the wrong spot will shade out your vegetables or sit in standing water. Soil that is too dense or too poor will stunt growth. Getting these two things right before you build saves you from tearing it down later.

Key Takeaways

  • Pick a location that gets at least six to eight hours of direct sun, is level or nearly level, and drains well after rain.
  • Build the frame from untreated wood or composite boards using corner brackets or 3-inch screws, then level it before filling.
  • Fill the bed with a mix of topsoil, compost, and peat moss or coconut coir in roughly equal parts, not garden soil alone.
  • Water the soil after filling and let it settle for a few days before planting, because it will compact and drop.
  • Start with shallow-rooted crops like lettuce and herbs if this is your first bed, or root vegetables if you have 12 inches of depth.

Choose a location that gets enough sun and drains well

Vegetables need light. Most leafy greens and herbs will tolerate four to six hours of sun, but tomatoes, peppers, squash, and beans need six to eight hours of direct sun daily. Walk your yard at 9 a.m. and 3 p.m. to see where shadows fall. If a tree or building will shade your bed in summer, move it.

Check drainage by pouring water on the spot where you plan to build. If it pools and sits for more than an hour, the ground underneath is compacted or clay-heavy. You can still build there, but you will need to either dig out the compacted layer underneath the bed or add drainage holes to the bottom of your frame. Most people choose a different spot instead.

Avoid low spots where water runs during heavy rain. Raised beds sit above grade, but water still finds them. A bed at the bottom of a slope will become a bog. Place it on level or gently sloping ground, or on a slight rise if your yard is wet.

Build the frame from untreated wood or composite materials

Use untreated lumber or composite boards. Treated wood (stamped with "pressure-treated") contains chemicals that can leach into soil over time. Cedar and redwood are naturally rot-resistant and safe, but expensive. Untreated pine or fir works fine for five to ten years before rotting. Composite boards (made from wood fiber and plastic) last longer and do not rot, but cost more upfront.

A standard bed is 4 feet by 8 feet by 12 inches deep. You can build smaller (2 by 4 feet) or larger, but 4 by 8 is straightforward to reach across and fits standard soil bag quantities. For a 4-by-8 bed, you need four boards: two 8-foot pieces and two 4-foot pieces.

Assemble the frame on the ground. Lay the boards in a rectangle. Drill pilot holes at each corner to prevent splitting, then drive 3-inch wood screws through the end of one board into the end of the adjacent board. Use at least two screws per corner. Alternatively, use L-shaped corner brackets bolted to the inside of the frame—these are faster and stronger. Once assembled, place the frame in your chosen location and use a level to check that it sits flat. Adjust by adding or removing soil underneath.

Fill the bed with the right soil mix, not garden soil alone

Garden soil is too dense for a raised bed. It compacts, drains poorly, and roots struggle to push through. Instead, use a mix of three ingredients in roughly equal parts: topsoil, compost, and peat moss or coconut coir. This creates a light, fluffy texture that drains well but holds moisture.

For a 4-by-8-by-12-inch bed, you need about 32 cubic feet of soil. That is roughly 1.2 cubic yards. A cubic yard of topsoil weighs about 1,300 pounds, so order by the bag if you do not have a truck. Most garden centers sell bags of topsoil, compost, and peat moss. Buy them in equal volumes—if you buy 10 bags of topsoil, buy 10 bags of compost and 10 bags of peat moss.

Dump all three into the bed and mix with a shovel until the color is even. Water the mix as you go. The soil will settle over a few days, so fill the bed slightly higher than the rim. After a week, add more mix to bring it back to the top.

Water and settle the soil before planting

After filling, water the entire bed until the soil is damp throughout. This helps the mix settle and reveals any low spots. The soil will drop noticeably—sometimes by 2 to 3 inches. Wait three to five days, then add more soil mix to bring the level back up.

Do not plant when ready after filling. The soil is still loose and will continue to settle under the weight of water and plant roots. Waiting a few days lets it compact naturally. If you plant right away, seedlings will sink as the soil settles beneath them, and their roots may end up too deep.

Plant vegetables suited to your bed depth and season

A 12-inch-deep bed works for most vegetables, but some are easier to start with. Lettuce, spinach, arugula, and herbs like basil and parsley need only 6 to 8 inches of depth. Carrots, beets, and radishes need 10 to 12 inches. Tomatoes, peppers, and squash need 12 inches minimum and benefit from 18 inches.

If your bed is 12 inches deep, start with leafy greens and herbs in spring, then plant root vegetables in summer for a fall harvest. Save tomatoes and peppers for a deeper bed or for next year. This spreads your learning and gives you a harvest sooner.

Plant from transplants (seedlings from a nursery) rather than seeds if this is your first bed. Transplants are more forgiving and produce faster. Space them according to the seed packet or plant label—do not crowd them. Crowded plants compete for water and nutrients and attract pests.

Maintain the bed through the season

Water deeply and regularly. A raised bed drains faster than in-ground soil, so check it every two to three days in hot weather. Water in the morning so foliage dries before dark, which reduces fungal disease. Soak the soil, not the leaves.

Add compost or aged manure as a top dressing in mid-season. As plants grow, they pull nutrients from the soil. A 1-inch layer of compost worked gently into the top few inches refreshes the bed without replacing it entirely.

Pull weeds as soon as you see them. A raised bed with good soil is attractive to weeds too. Removing them young prevents them from setting seed and competing with vegetables. At the end of the season, do not empty the bed. Leave it as is or add a 2-inch layer of compost. The soil will be even richer next year.

Frequently Asked Questions

How deep does a raised bed need to be?

Most vegetables need 10 to 12 inches. Leafy greens and herbs need 6 to 8 inches. Root vegetables like carrots and beets need 12 inches. Tomatoes and peppers do better with 18 inches, but will produce in 12 if the soil is rich.

Can I use treated wood for a raised bed?

Modern pressure-treated lumber is safer than older versions, but untreated wood, cedar, redwood, or composite boards are better choices for vegetables. Treated wood can leach chemicals into soil over time, especially in acidic soil or with frequent watering.

What if my raised bed is in partial shade?

Leafy greens, lettuce, spinach, and herbs tolerate four to six hours of sun. Tomatoes, peppers, squash, and beans need six to eight hours. If your bed gets only three to four hours, stick to greens and herbs. If it gets eight or more, you can grow anything.

How often should I water a raised bed?

Check the soil 2 inches down with your finger. If it is dry, water deeply until water drains from the bottom. In hot weather, this may be every two to three days. In cool or rainy weather, once a week or less. Soil in a raised bed dries faster than ground soil, so it needs more frequent watering.

Do I need to replace the soil every year?

No. Add 1 to 2 inches of compost or aged manure each year to refresh nutrients. After three to five years, you may want to replace the top 6 inches if it has compacted heavily. Most gardeners keep the same bed for many years, just adding compost annually.