A DIY above ground planter, also called a raised garden bed, is a wooden, concrete, or metal frame placed on level ground and filled with quality soil to bypass poor native soil completely.
Bad soil sinks more gardens than bad weather. A raised bed lets you skip the rocky clay or builder-grade fill dirt that comes with most suburban lots and grow in a mix you control. The best part is a weekend’s work gets you a bed that lasts for seasons. The table below shows what the three main build methods cost and how long they hold up.
| Build Method | Approximate Cost | Typical Lifespan |
|---|---|---|
| Wood (cedar or redwood) | $100–$300 | 8–12 years |
| Concrete block | $50–$150 | Decades |
| Corrugated metal | $150–$250 | 15+ years |
| Pine (treated or painted) | $60–$120 | 3–5 years |
| Elevated bed on legs | $120–$250 | 6–10 years |
| Kit (all-in-one box) | $80–$400 | 4–8 years |
| DIY from scrap lumber | $20–$60 | 1–3 years |
Which Material Works Best For Your Yard
Cedar and redwood are the gold standard for wood beds because they resist rot without chemical treatments. A 4-by-8-foot cedar bed takes nine 8-foot 2×6 boards and four 4×4 corner posts cut to the bed height. Concrete retaining-wall blocks stacked on a level pad cost less upfront and never rot — just slide 2×6 boards into the block notches. Corrugated metal gives a modern look on a pressure-treated lumber frame, but keep the treated wood out of direct contact with edible soil by lining the interior.
If your yard has burrowing pests like gophers, staple hardware cloth or chicken wire to the bottom of any wood bed before filling it. Line the interior walls with landscape fabric to keep soil from washing out through the gaps.
The Smart Dimensions To Start With
Width is the most important number. Keep any bed 4 feet wide or less so you can reach the center without stepping in and compacting the soil. Depth depends on what you grow: 10 inches handles most vegetables, but carrots, potatoes, and deep-rooted tomatoes prefer 16 inches. Length is flexible — 4 to 8 feet works for most yards.
Between beds, leave at least 28 inches of pathway (36 to 48 inches is better) so a wheelbarrow fits and tall plants don’t shade their neighbors.
How Much Soil A Standard Bed Needs
Use the formula Length x Width x Depth to calculate any bed size. Buy a labeled “triple mix” (topsoil, rotted compost, and peat moss) or blend your own with 60% topsoil, 30% compost, and 10% potting mix for vegetables. Never fill a bed with standard topsoil alone — it packs down hard and lacks the organic matter roots need.
How To Build A Cedar Raised Bed In One Morning
Measure and cut two 8-foot boards for the long sides and two 4-foot boards for the short sides. Screw the short boards into the ends of the long boards — soil pressure pushes outward on the long sides, so the screws are under tension rather than being pulled straight out. Attach the 4×4 corner posts flush with the long ends and set back 1.5 inches from the short ends.
Set the frame on the spot you cleared. Dig out high spots until the frame sits level in every direction — a wobbly bed cracks at the joints over time. Before you fill it, check underground utility lines by calling 811 in the US. No one wants to dig a garden bed onto a gas line.
If you are comparing plans and prices before you start building, see our top-rated above ground planter picks for designs that skip the DIY guesswork.
Concrete Block Method: Cheaper, Sturdier, Permanent
This method skips power tools and pour-and-wait concrete. Buy retaining-wall blocks with notches — place one at each corner on level ground with the open hole facing up. Slide 2×6 boards into the notches, check square by measuring diagonals (they must match), then hammer 18-inch rebar through the center hole into the ground, leaving 4 to 5 inches showing to pin the structure. Stack a second layer of blocks with holes facing down and add a second course of boards for a deeper bed.
Common Mistakes That Ruin A Raised Bed
- Building over 4 feet wide. You can’t reach the middle without stepping in and compacting the soil.
- Using topsoil from a bag. Standard topsoil has almost no structure or nutrients. Spend the extra few dollars on triple mix or garden soil.
- Screwing long boards into short boards. The joint fails because outward soil pressure pulls the fasteners straight out. Short boards always get screwed into the long boards’ ends.
- Forgetting drainage. Leave gaps between bottom slats or staple hardware cloth so water drains freely. Soggy soil kills roots.
- Placing tall plants on the south side. Eight-foot tomatoes shade every low-growing pepper behind them. Plan plant height from north to south.
Elevated Planter Box: The Option For Bad Knees Or Decks
An elevated bed with legs puts the soil at waist height and protects the surface below. The frame uses eight pieces cut to 3 feet 11.75 inches for the long sides, eight pieces cut to 3 feet 4 inches for the short sides, and four 36-inch legs. Attach the legs at the corners with cross-bracing, line the bottom with hardware cloth, and fill it with the same triple mix you would use for a ground-level bed. An elevated planter works well on a patio, deck, or balcony where digging is impossible.
Water established raised beds with about one inch of water per week, more during hot dry spells. The soil in a raised bed warms faster in spring than ground soil, so you can plant a week or two earlier than neighbors who dig straight into the yard.
Finish With The Right Fill And Watering Routine
Fill the bed with your triple mix or the 60/30/10 vegetable blend, leave a couple of inches at the top for mulch or compost, and water deeply right after planting. A soaker hose laid along the surface before mulching saves hours of hand watering over the summer. Check soil moisture by pushing a finger two inches down — if it feels dry, water.
FAQs
Does a raised bed need a bottom?
A bottom is optional for ground-level beds. Hardware cloth stapled underneath keeps gophers and moles out while draining water freely. Elevated beds on legs need a solid bottom lined with landscape fabric or hardware cloth to hold the soil in.
Can I use pressure-treated lumber for a vegetable bed?
Modern pressure-treated lumber is safe for vegetable gardens under recent EPA guidelines, but many gardeners still prefer untreated cedar or concrete to avoid any risk. If you use treated lumber, line the interior walls with heavy plastic or landscape fabric so soil does not contact the wood directly.
What is the cheapest way to build an above ground planter?
Concrete retaining-wall blocks with salvaged lumber boards are the cheapest method at roughly $50 per bed. Repurposing scrap lumber or untreated pine also keeps costs low, though pine must be painted or charred to last more than a couple of seasons.
How deep does a raised bed need to be for tomatoes?
Determinate tomatoes need at least 12 inches of soil depth, and indeterminate varieties do best at 16 to 18 inches. A 10-inch-deep bed works for lettuce, spinach, and most herbs, so plan depth based on what you grow most.
Should I remove grass before placing the bed on top?
Laying cardboard directly over the grass kills it by blocking sunlight while it decomposes into organic matter. You can skip double digging entirely — just wet the cardboard, set the frame on top, and fill with soil. The grass dies within two to four weeks.
References & Sources
- Eartheasy. “How to Build a Raised Garden Bed: Best Kits and DIY Plans.” Covers standard dimensions, material recommendations, and wood construction steps with a detailed cut list.
- Driven by Decor. “Inexpensive Raised Garden Bed Ideas.” Step-by-step instructions for the concrete block method using retaining wall blocks and 2×6 boards.
- Love & Renovations. “How To Build A DIY Raised Garden Bed.” Correct screw order for joint strength and cardboard method for weed suppression.
- Homestead & Chill. “How to Build a Raised Garden Bed.” Detailed instructions for hardware cloth attachment and recommended spacing between beds.
- Northern Gardener. “Building a Raised Bed with Legs.” Cut list and assembly method for elevated planter boxes suited for decks and patios.