Start with a frame, soil, and a level spot

A raised bed is a contained garden box you fill with soil and plant into—it sits above ground level, usually between 6 and 12 inches high. To build one, you need four pieces of untreated wood (cedar and redwood resist rot longer than pine), a drill or screws, a level, and a location that gets at least six hours of direct sun per day. Assemble the frame by screwing the boards together at the corners, set it on bare ground or cardboard, and check that the top edges are level using a spirit level.

The soil matters more than the frame. Fill your bed with a mix of topsoil, compost, and peat moss or coconut coir in roughly equal parts. This blend drains well but holds moisture, and it's loose enough for roots to push through. You'll need more soil than you expect—a 4-by-8-foot bed that's 10 inches deep holds about 27 cubic feet of soil. Avoid garden soil from your yard; it compacts and often contains weed seeds.

Location is the third piece. Most vegetables need six to eight hours of sun. If your yard is shaded, choose a spot that gets morning sun and afternoon shade, or grow leafy greens and herbs instead of tomatoes. Make sure water can drain away from the bed—don't build in a low spot where rain pools.

Key Takeaways

  • Build your frame from untreated wood, screw the corners together, and check that the top is level before filling it with soil.
  • Fill the bed with a mix of topsoil, compost, and peat moss or coconut coir in equal parts, not soil from your yard.
  • Choose a spot that gets six to eight hours of direct sun and drains well, away from tree roots and low spots.
  • Plant seeds or seedlings at the depth and spacing shown on the seed packet or plant label, and water until the soil is moist but not soggy.
  • Add 1 to 2 inches of compost to the top of the bed each spring to replace nutrients and improve soil structure.

Prepare the bed before planting

Once your frame is built and filled, let the soil settle for a few days. Water it thoroughly so it compacts slightly and you can see where it actually sits. If the soil level drops more than an inch, add more. The soil should be moist but not waterlogged when you plant.

Before you put seeds or seedlings in, remove any rocks, sticks, or debris from the top few inches. If you're planting over grass or weeds, lay cardboard on the ground under the frame first—it breaks down over time and blocks weeds from growing up into your bed. You don't need to remove the cardboard; it becomes part of the soil.

Plant seeds or seedlings at the right depth

The seed packet or plant label tells you exactly how deep to plant and how far apart. Follow those instructions—they're based on how the plant grows. Large seeds like beans and squash go deeper (1 to 2 inches); tiny seeds like lettuce and carrots go shallow (a quarter inch or less). Space plants according to the label so they have room to grow without crowding.

If you're starting from seeds, plant them directly into the bed. If you're using seedlings from a nursery, dig a hole the same depth as the pot, slide the plant in, and firm the soil around it. Water gently after planting so the soil settles around the roots without washing them away.

Water consistently without overwatering

Raised beds dry out faster than in-ground gardens because soil is exposed on all sides. Check the soil 2 inches down with your finger—if it feels dry, water. If it feels moist, wait. Most vegetables need about 1 inch of water per week, either from rain or from you. Water in the early morning so leaves dry quickly and fungal diseases are less likely to take hold.

Use a soaker hose or drip line if you can—it delivers water directly to the soil and wastes less than overhead watering. If you use a sprinkler or watering can, water the soil, not the leaves. Wet foliage invites mildew and other problems. In hot weather, you may need to water every day; in cool weather or after rain, you may skip several days.

Feed the soil and manage weeds

Raised beds lose nutrients as plants grow and as rain and watering wash them down. Each spring, spread 1 to 2 inches of finished compost over the top of the bed and work it gently into the top few inches of soil. This replaces what was used and improves the soil structure. You can also add compost in mid-summer if plants look pale or weak.

Weeds will still appear, but a raised bed makes them easier to pull because the soil is loose and you're not bending as far. Pull them when they're small, before they set seed. Mulch around plants with 2 inches of straw or shredded leaves to block sunlight from reaching weed seeds and to keep soil moist longer.

Rotate crops and plan for next year

At the end of the season, pull out dead plants and add them to a compost pile if they're healthy, or throw them away if they were diseased. Don't plant the same family of vegetables in the same spot year after year—tomatoes, peppers, and eggplants are all in the same family, as are cabbage, broccoli, and kale. Moving them around prevents soil-borne diseases from building up.

A straightforward rotation is to divide your bed into three or four sections and plant a different crop family in each one each year. Keep notes on what you planted where so you don't repeat by accident. In fall, add a 2-inch layer of compost to the bed and let it sit over winter—by spring, it will have broken down and enriched the soil.

Troubleshoot common problems

If plants look pale or yellow, they may need nitrogen. Compost adds some, but a balanced fertilizer (like a 10-10-10 mix) gives a quick boost. If leaves have holes or are chewed, look for insects on the undersides of leaves. Hand-pick larger pests like beetles and caterpillars, or spray with neem oil if the problem is severe. If plants wilt even though the soil is moist, the roots may be rotting from too much water—improve drainage by adding perlite or sand to the soil next season.

If seedlings fall over and die near the soil line, they have damping-off, a fungal disease. Prevent it by not overwatering, spacing plants so air circulates, and using fresh soil rather than reusing old soil without adding compost. If a whole section of the bed fails, it's often because the soil is compacted or depleted—add compost and loosen the soil with a garden fork before replanting.

Frequently Asked Questions

How often should I water a raised bed?

Check the soil 2 inches down with your finger. If it feels dry, water. If it feels moist, wait. Most vegetables need about 1 inch of water per week total, from rain or watering combined. In hot weather you may water daily; in cool weather or after rain, you may skip several days.

Can I use treated wood for the frame?

No. Treated wood contains chemicals that can leach into soil and plants. Use untreated cedar, redwood, or composite boards instead. Cedar and redwood last 10 to 15 years; pine lasts 5 to 10 years before rotting.

What do I do if my raised bed is in partial shade?

Grow leafy greens, herbs, and root vegetables like lettuce, spinach, kale, parsley, and carrots. They tolerate four to six hours of sun. Tomatoes, peppers, and squash need six to eight hours of direct sun and won't produce well in shade.

Do I need to replace all the soil each year?

No. Add 1 to 2 inches of compost each spring to replace nutrients and improve structure. After five to seven years, the original soil will have broken down significantly, and you can replace the bottom half if it looks compacted or depleted.

Can I build a raised bed on top of grass?

Yes. Lay cardboard under the frame to block grass and weeds from growing up into the bed. The cardboard breaks down over time and becomes part of the soil. You don't need to remove it.