Start with the frame, soil, and a level spot

A raised bed garden is a wooden, metal, or composite box filled with soil that sits above ground level. You build the frame first, fill it with soil, then plant directly into it. The whole project takes a weekend, and you do not need to dig into your existing yard or remove sod—the raised bed sits on top of whatever is underneath.

Choose a location that gets at least six hours of direct sunlight daily for vegetables, or three to four hours for leafy greens. Check that the spot is relatively level; a bed that tilts will have shallow soil on one side and waterlogged soil on the other. If the ground slopes, you can level it by digging out the high side and filling the low side, or straightforward accept a slight tilt and adjust your watering.

Measure the space you have. A 4-by-8-foot bed is standard and straightforward to reach from both sides. A 4-by-4-foot bed works for smaller yards. Avoid beds wider than 4 feet unless you plan to step into them—you should be able to reach the center from the edge without straining.

Key Takeaways

  • Build a frame from untreated wood, composite boards, or galvanized metal, then fill it with a mix of topsoil, compost, and peat moss or coconut coir.
  • Position your bed where it receives at least six hours of sunlight and sits on level or nearly level ground.
  • Fill a 4-by-8-foot bed with roughly 32 cubic feet of soil, which you can buy pre-mixed or combine yourself from bulk suppliers.
  • Plant seeds or transplants directly into the raised bed soil once it has settled for a few days after filling.
  • Water from the soil surface, not the leaves, and mulch the top 2 to 3 inches to retain moisture and suppress weeds.

Choose your frame material and build it

Untreated wood is the most common choice. Use cedar, redwood, or composite boards rated for ground contact. Avoid pressure-treated lumber from before 2004, which contains arsenic; newer pressure-treated wood is safer but still not ideal for vegetable beds. Cedar and redwood naturally resist rot and last 10 to 15 years. Composite boards made from wood fiber and plastic last 20 years or longer but cost more upfront.

For a 4-by-8-foot bed, you need two 8-foot boards and two 4-foot boards, all at least 10 to 12 inches tall. Lay them flat on the ground in a rectangle, then fasten the corners with galvanized corner brackets and bolts, or with 3-inch galvanized deck screws driven through the end grain. Do not use regular nails—they will pull loose as the wood shifts.

Metal beds made from galvanized steel or aluminum are rust-resistant and last indefinitely. They cost more than wood but require no maintenance. Composite beds are lightweight and do not rot, though they can fade in direct sun. Both are assembled the same way: fasten the corners with bolts or the hardware provided.

Once the frame is assembled, set it in place and check that it is level with a 2-foot level. Adjust by adding or removing soil underneath, not by forcing the frame.

Fill the bed with the right soil mix

Do not use garden soil from your yard. Raised beds need a soil mix that drains well, holds moisture, and is loose enough for roots to penetrate. A standard mix is one-third topsoil, one-third compost, and one-third peat moss or coconut coir. Some gardeners use a 50-50 mix of topsoil and compost, which also works.

Calculate how much soil you need: multiply length × width × depth in feet, then divide by 27 to get cubic yards. A 4-by-8-foot bed that is 12 inches deep needs 32 cubic feet, or about 1.2 cubic yards. Buy soil in bulk from a landscape supplier if you can; it is cheaper than bags and easier to move with a wheelbarrow. If you buy bags, expect to need roughly 50 bags of 40-pound soil for that same bed.

Dump the soil into the frame and rake it level. Water it lightly and let it settle for two to three days before planting. The soil will compact slightly, and you may need to add a bit more to bring it back to the top of the frame.

Plant seeds or transplants into the bed

Once the soil has settled, you can plant. For vegetables, follow the spacing and depth on the seed packet or transplant label. Tomatoes, peppers, and eggplants go in as transplants (small plants from a nursery) spaced 18 to 24 inches apart. Lettuce, spinach, and arugula can be direct-seeded and thinned as they grow. Beans, peas, squash, and cucumbers are usually direct-seeded.

Push seeds or transplants into the soil at the depth specified on the packet. Water gently so the soil settles around the roots without washing them out. If you are planting transplants, water them in the pot first, then plant them at the same depth they were growing in the pot—not deeper, or the stem will rot.

Space plants according to their mature size, not their current size. A tomato that is 6 inches tall now will be 5 feet tall at harvest, so give it room. Crowding leads to poor air circulation and disease.

Water and mulch to keep plants healthy

Raised beds drain faster than in-ground gardens, so they need more frequent watering. Water at the soil surface, not the leaves, to avoid fungal disease. In hot weather, you may need to water daily. In cool weather or after rain, check the soil 2 inches down with your finger—if it is moist, skip watering.

Add 2 to 3 inches of mulch on top of the soil around your plants. Use straw (not hay, which contains seeds), shredded leaves, or wood chips. Mulch keeps the soil cool, reduces evaporation, and suppresses weeds. Keep mulch 2 inches away from plant stems to prevent rot.

In the first year, your bed will settle and compact. You may need to add more soil in spring of the second year. After that, add 1 to 2 inches of compost each spring to replenish nutrients and maintain the soil level.

Manage weeds and pests in a raised bed

Raised beds have fewer weeds than in-ground gardens because you are starting with clean, purchased soil. Any weeds that do appear are straightforward to pull because the soil is loose. Pull them when they are small, before they set seed.

Pests like slugs, aphids, and beetles can still find your bed. Check plants regularly for damage or insects. Hand-pick larger pests like beetles and caterpillars. For aphids or spider mites, spray the undersides of leaves with water from a hose, or use insecticidal soap if the problem is severe. Encourage beneficial insects like ladybugs by planting flowers nearby.

If you notice disease—yellowing leaves, spots, or wilting—remove the affected leaves or plant. Improve air circulation by spacing plants properly and pruning lower leaves. Water only at the soil surface to keep foliage dry.

Prepare your bed for winter and next season

At the end of the growing season, pull out dead plants and add them to a compost pile if they are disease-free. Leave healthy plant material in the bed to break down over winter, or add a layer of compost on top. This enriches the soil for next year.

In cold climates, you can plant a cover crop like clover or winter rye in fall. It will grow slowly through winter and can be turned into the soil in spring, adding nitrogen and organic matter. In mild climates, you can plant cool-season crops like lettuce, kale, and broccoli through fall and winter.

Check the frame each spring for rot or damage. Tighten bolts if they have loosened. If wood boards are rotting, replace them—you do not need to empty the bed, just unbolt the damaged board and slide in a new one.

Frequently Asked Questions

How deep should a raised bed be?

Most vegetables need 10 to 12 inches of soil. Shallow-rooted crops like lettuce and herbs can grow in 6 to 8 inches. Deep-rooted crops like tomatoes, carrots, and parsnips prefer 12 to 18 inches. If you are building on compacted soil or clay, go deeper to give roots room to escape into the native soil below.

Can I use leaves or grass clippings as mulch?

Shredded leaves work well and break down into the soil, adding organic matter. Whole leaves mat down and can trap moisture. Grass clippings are fine if they come from a lawn that has not been treated with herbicides. Avoid hay, which contains weed seeds.

What if my raised bed is in partial shade?

Leafy greens, herbs, and root vegetables tolerate three to four hours of sun. Tomatoes, peppers, and squash need six hours or more. If your bed gets only two to three hours of sun, stick to shade-tolerant crops like lettuce, spinach, kale, and mint.

Do I need to add fertilizer to a raised bed?

A new bed filled with compost-rich soil has enough nutrients for the first season. In year two and beyond, add 1 to 2 inches of compost each spring, or use a balanced fertilizer like 10-10-10 once plants are established. Heavy feeders like tomatoes and squash may need extra fertilizer mid-season.

Can I reuse the soil from my raised bed year after year?

Yes. Each year, add compost or aged manure to replenish nutrients and organic matter. After five to seven years, the soil may become compacted or depleted. At that point, remove the top 6 inches, replace it with fresh compost, and continue. Or empty the entire bed and start fresh with new soil.