Build your raised bed frame first, then fill it with soil
A raised bed garden starts with a wooden or composite frame sitting on top of the ground. You build or buy the frame, set it in place, line the bottom if you want to block weeds, and fill it with garden soil. The whole process takes a few hours for a single bed, and you can plant the same day you finish filling it. Most people use untreated wood boards, composite lumber, or galvanized metal, all of which last several years before needing replacement.
The frame itself is the main structural work. A typical bed is 4 feet long, 2 feet wide, and 12 inches deep—large enough to grow vegetables or flowers without reaching too far to the center, but small enough to move soil and plants around easily. You can make it any size, but anything wider than 3 feet becomes hard to reach across, and anything shallower than 10 inches limits what you can grow.
Key Takeaways
- Build or buy a frame from untreated wood, composite lumber, or galvanized metal, then position it on level ground where it will get at least six hours of direct sun per day.
- Line the bottom with hardware cloth or landscape fabric if you want to block burrowing pests or prevent weeds from growing up through the soil.
- Fill the bed with a mix of topsoil and compost rather than garden soil alone, because garden soil compacts over time and drains poorly when confined.
- Water the soil after filling and let it settle for a day or two before planting, because new soil shifts and compacts as it absorbs water.
- Position your bed where it receives at least six hours of sun for vegetables, or three to four hours for leafy greens and herbs.
Choose a location with good sun and level ground
Raised beds need at least six hours of direct sunlight per day if you are growing vegetables. Leafy greens and herbs can manage with three to four hours. Before you build, spend a day watching how the sun moves across your yard. Look for a spot that gets morning sun—it dries dew and helps prevent fungal disease—and is not shaded by trees or buildings during the afternoon.
The ground underneath should be as level as possible. If your yard slopes, you can build the bed anyway, but you will need to dig out the high side and use the soil to build up the low side so the frame sits flat. A bed that tilts will hold water unevenly and make it hard to water plants fairly. Use a long level or a straight board and a level to check before you start building.
Avoid placing the bed directly against your house or under a gutter downspout. Water running off the roof can flood the bed or wash soil away, and the bed can trap moisture against your foundation. A few feet away is safer.
Build or assemble the frame
If you are building from scratch, use untreated wood boards—typically 2-by-12 lumber for a 12-inch-deep bed. Avoid pressure-treated wood, which contains chemicals that can leach into soil over time. Cedar and redwood are naturally rot-resistant and last longer, but they cost more. Pine and fir work fine for three to five years, then the wood begins to rot and you replace the boards.
Assemble the frame by laying the boards in a rectangle and fastening the corners. Use galvanized or stainless steel screws (not nails, which pull loose as wood shrinks) and a power drill. Drill pilot holes first so the wood does not split. You need four corner brackets or four screws per corner—two screws per board end, driven into the board it meets. The frame does not need a bottom; the soil sits directly on the ground.
If you do not want to build, composite raised bed kits are sold at garden centers and online. They assemble in 30 minutes and last 10 to 15 years. Galvanized metal beds are also available and work well, though they can get hot in direct sun and may rust at the seams after several years.
Line the bottom to block weeds and pests
Lining the bottom is optional but useful. A layer of hardware cloth (a metal mesh with half-inch openings) stops burrowing rodents from tunneling up into your bed. Landscape fabric stops weeds from growing up through the soil, though it also slows drainage slightly. You can use both: hardware cloth on the bottom, landscape fabric on top of it.
If you use hardware cloth, cut it to fit the inside of the frame and lay it flat on the ground. Overlap the seams by a few inches and staple it to the inside of the wooden frame so it does not shift when you add soil. Landscape fabric goes on top and can be stapled the same way, or straightforward weighted down with soil as you fill the bed.
If you skip the lining, perennial weeds and grass will eventually grow up from below, and you will need to pull them or spray them. Many gardeners accept this trade-off to save time and money.
Fill the bed with soil and compost
Do not use garden soil straight from a bag. It compacts when confined in a raised bed and drains poorly. Instead, mix topsoil and compost in roughly equal parts. A 4-by-2-foot bed that is 12 inches deep holds about 8 cubic feet of soil. You can buy soil by the cubic foot or by the bag—most bags are 1 to 2 cubic feet. Calculate how much you need before you buy, because hauling extra bags is work.
Dump the soil and compost into the bed and mix it with a shovel or garden fork. Break up any clumps. The mix should be loose and crumbly, not dense. If it feels heavy and clay-like, add more compost. If it feels sandy and drains too fast, add more topsoil.
Water the soil thoroughly after filling. It will settle and compact as it absorbs water. Wait a day or two, then add more soil if the level drops noticeably. This settling is normal and happens only once, when the soil is new.
Prepare the bed for planting
After the soil has settled, you can plant seeds or transplants. If you are planting seeds, rake the surface smooth and follow the spacing on the seed packet. If you are planting transplants (seedlings from a nursery), dig a hole slightly larger than the root ball, set the plant in, and firm the soil around it.
Water gently after planting. New transplants need consistent moisture for the first week or two while they establish roots. Seeds need to stay moist until they sprout, which usually takes 7 to 14 days depending on the plant.
Add a 2-inch layer of mulch—wood chips, straw, or shredded leaves—around plants (but not touching the stems). Mulch keeps soil moist, moderates temperature, and slows weed growth. As mulch breaks down over the season, it adds organic matter to the soil, which improves it for next year.
Maintain the bed through the season
Water when the top inch of soil feels dry to your finger. In hot weather, that may be every day. In cool weather or after rain, you may not need to water for several days. Raised beds drain faster than in-ground gardens, so they dry out quicker and need more frequent watering.
Pull weeds as they appear. The loose soil in a raised bed makes weeds straightforward to pull, roots and all. Do it weekly so they do not take over.
At the end of the season, add compost or aged manure to the top of the bed. You do not need to dig it in. Over winter, it breaks down and mixes with the existing soil, enriching it for next year. This yearly addition keeps the soil loose and fertile without needing to replace it entirely.
Frequently Asked Questions
How deep does a raised bed need to be?
Most vegetables need at least 10 to 12 inches of soil. Root crops like carrots and beets need 12 inches or more. Leafy greens and herbs can grow in 8 inches. Shallower beds work but limit what you can grow and dry out faster.
Can I use treated wood for the frame?
Pressure-treated wood contains chemicals that can leach into soil. Untreated wood, cedar, or composite materials are safer. If you already have a treated wood bed, lining it with landscape fabric reduces contact between the wood and soil.
What if my yard is too shady for vegetables?
Leafy greens like lettuce, spinach, and kale grow well in three to four hours of sun. Herbs like parsley, mint, and chives also tolerate partial shade. Tomatoes, peppers, and squash need full sun and will not produce well in shade.
How often should I replace the soil?
You do not need to replace it. Add 2 to 3 inches of compost each year, and the bed stays fertile. After five to ten years, if the soil feels compacted or depleted, you can remove the top layer and replace it, or empty the whole bed and start fresh.
Do I need to add fertilizer?
If you fill the bed with compost and topsoil, and add compost yearly, most vegetables get enough nutrients. If plants look pale or weak mid-season, a balanced fertilizer or compost tea can help. Avoid synthetic fertilizers in raised beds; they can build up salts over time.