Start with the frame and location
A raised bed is a wooden or composite box you fill with soil and plant into. The first step is choosing where to put it and building or buying the frame. Pick a spot that gets at least six hours of direct sunlight for vegetables, or three to four hours for leafy greens. The ground should be relatively level — a slope of more than a few degrees will cause water to pool on one side.
You can build a frame from untreated wood boards (cedar, redwood, or pine last longest), composite lumber, or galvanized metal. If you build from wood, use boards at least two inches thick and eight to twelve inches tall. Screw or bolt the corners together — nails work but loosen over time. Alternatively, buy a pre-made kit that arrives flat and assembles in under an hour with a screwdriver.
Set the frame directly on the ground. Do not dig it into the soil — the wood or composite will rot faster if buried. If you want a barrier between the raised bed soil and the ground below (to stop weeds or separate contaminated soil), lay landscape fabric or cardboard on the ground first, then set the frame on top.
Key Takeaways
- Choose a location with at least six hours of sunlight and level ground, then assemble the frame using untreated wood, composite, or metal.
- Lay landscape fabric or cardboard under the frame to block weeds and separate your new soil from the ground beneath.
- Fill the bed with a mix of topsoil, compost, and peat moss or coconut coir in roughly equal parts, or use a pre-mixed raised bed soil.
- Water the soil thoroughly after filling, then let it settle for a few days before planting seeds or transplants.
- Position the bed where you can reach the center without stepping into it, since compacted soil drains poorly and damages plant roots.
Fill the bed with soil and amendments
Once the frame is in place, fill it with soil. Do not use soil from your yard alone — it compacts, drains poorly, and may contain weed seeds or disease. Instead, mix three ingredients in roughly equal parts: topsoil (the dark, nutrient-rich soil sold in bags), compost (aged organic matter that feeds plants), and peat moss or coconut coir (which holds water and air). A four-by-eight-foot bed that is ten inches deep needs about twenty cubic feet of soil, or roughly forty bags of bagged soil if you buy it pre-mixed.
If mixing by hand, dump each ingredient into the bed and stir with a shovel until the color is uniform. If you prefer not to mix, buy pre-made raised bed soil from a garden center or online — it arrives in bulk or bags and is ready to use. Either way, fill the bed to within an inch of the top rim.
Water the soil thoroughly after filling. It will settle over the next few days as the water moves through it and the materials compact slightly. You may need to add more soil after a week to bring it back to the original level. Do not plant until the soil has settled and drained.
Prepare the soil for planting
Before you plant, test the soil if you can. A straightforward soil test kit from a garden center tells you the pH (acidity or alkalinity) and the levels of nitrogen, phosphorus, and potassium. Most vegetables prefer a pH between 6.0 and 7.0. If your soil is too acidic, add lime; if too alkaline, add sulfur. Follow the kit instructions for how much to add.
If you do not test, assume the pre-mixed soil is balanced and add a two-inch layer of compost on top before planting. This feeds the soil as plants grow and improves drainage. Work it into the top few inches with a shovel or garden fork.
Let the bed sit for at least three days after filling and watering before you plant seeds or transplants. This allows the soil to settle fully and any air pockets to close. If you plant when ready, the soil will sink further as you water, leaving roots exposed or buried too deep.
Decide on bed dimensions and depth
The width of your bed matters because you need to reach the center without stepping into it. A bed wider than four feet forces you to lean too far or step on the soil, which compacts it and damages roots. Most gardeners use beds that are three to four feet wide and as long as space allows — six to eight feet is common.
Depth depends on what you grow. Leafy greens and herbs need six to eight inches. Root vegetables like carrots and beets need eight to twelve inches. Tomatoes, peppers, and squash need twelve inches or more. If you are growing a mix, build the bed at least twelve inches deep so all plants have room.
Taller beds (eighteen to twenty-four inches) are easier on your back and warm up faster in spring, but they dry out more quickly and need more soil to fill. Shorter beds (six to eight inches) are cheaper and retain moisture longer, but you cannot grow deep-rooted plants.
Add irrigation or watering systems
Raised beds dry out faster than in-ground gardens because water drains through all sides. If you water by hand with a hose, water deeply two to three times a week in hot weather, less in cool weather. Water at the base of plants, not the leaves, to prevent disease.
For hands-off watering, install a soaker hose or drip line before you plant. Lay it on the soil surface in a coil or grid pattern, then cover it with mulch. Attach it to a timer and a water source. Soaker hoses deliver water slowly and directly to roots, using less water than overhead sprinklers and reducing disease.
Mulch the top of the bed with two to three inches of straw, wood chips, or shredded leaves. Mulch keeps soil cool, retains moisture, suppresses weeds, and breaks down into compost over time. Do not use fresh wood chips — they pull nitrogen from the soil as they decompose. Use aged chips or straw instead.
Position the bed for access and sun
Orient the bed so the long side faces south (in the Northern Hemisphere) or north (in the Southern Hemisphere). This maximizes sunlight exposure throughout the day. If you have limited space, east-west orientation is acceptable — it still provides adequate sun for most vegetables.
Leave at least two feet of clear space on all sides of the bed so you can walk around it, kneel beside it, and reach tools or supplies. If you plan multiple beds, space them three feet apart to allow a wheelbarrow or garden cart to pass between them.
Avoid placing the bed directly under trees or in the shade of buildings. Even if the bed itself gets sun, falling leaves and branches will shade it as the season progresses. Trees also compete for water and nutrients, and their roots can grow into the bed.
Maintain the bed structure and soil over time
Wood frames last five to fifteen years depending on the wood type and climate. Cedar and redwood last longer than pine. Check the frame each spring for rot, especially at the corners and where wood touches soil. If you see soft spots or discoloration, replace those boards before they fail.
The soil in a raised bed compacts and depletes over time. Each year, add one to two inches of compost to the top and work it into the upper few inches. This replenishes nutrients and improves structure. After three to five years, you may need to replace the entire soil if it becomes hard and drains poorly.
Rotate what you plant in each bed from year to year. Growing the same crop in the same spot depletes specific nutrients and builds up pests and diseases. A straightforward rotation — vegetables, then legumes, then root crops — keeps the soil healthy and reduces problems.
Frequently Asked Questions
Do I need to line the bottom of a raised bed?
A lining is optional. Landscape fabric or cardboard blocks weeds and separates your soil from contaminated ground, but it also slows drainage and can trap water. Use it if weeds are a major problem or if the ground below is contaminated. Otherwise, skip it and rely on the soil mix and mulch to suppress weeds.
How much does it cost to build a raised bed?
A four-by-eight-foot wooden frame costs thirty to eighty dollars depending on wood type. Soil to fill it costs sixty to one hundred twenty dollars. A pre-made composite kit costs one hundred to three hundred dollars but lasts longer. Total cost ranges from one hundred to four hundred dollars for a single bed, less if you build from scrap wood or buy soil in bulk.
Can I use treated wood for a raised bed?
Modern pressure-treated wood is safe for vegetable gardens — it no longer contains arsenic. However, untreated cedar or redwood is still preferable because it lasts longer and avoids any concern. If you use treated wood, line the bed with landscape fabric to add an extra barrier.
What if my raised bed is in a shady spot?
Move it if possible. Most vegetables need six hours of direct sun. If you cannot move it, grow shade-tolerant crops like lettuce, spinach, kale, parsley, and mint. These produce well in three to four hours of sun. Avoid tomatoes, peppers, and squash in shade — they will not fruit.
How often should I water a raised bed?
Water when the top inch of soil is dry to the touch. In hot weather, this is usually two to three times a week. In cool weather or after rain, it may be once a week or less. Soil in raised beds drains faster than ground soil, so check it often. Mulch helps retain moisture and reduces watering frequency.