How to Make an Above Ground Planter Box | A Weekend DIY Project

You can build a durable above-ground planter box for around $100 in a single weekend using cedar boards, 3-inch screws, and hardware cloth for drainage.

A well-built above ground planter box solves the most common garden problems in one go: poor native soil, back-breaking weeding, and unwanted burrowers. You get complete control over what goes in the bed, and the height saves your knees. The process breaks down into straightforward steps that a first-timer can finish in an afternoon.

What You Need For An Above Ground Planter Box

The right materials determine how many seasons this box lasts. Cedar is the gold standard for rot resistance, but it costs more than pressure-treated pine. If you use pine, line the interior to avoid chemical leaching into your soil.

• Lumber: Cedar 2×8 or 2×6 boards for the walls; 4×4 posts for corners (or 2x4s cut to wall height)
• Hardware: 3-inch #10 wood screws, 5/16-inch staples for the mesh
• Bottom: ¼-inch galvanized hardware cloth or chicken wire (keeps voles out)
• Liner: Landscape fabric or heavy-duty plastic (only if wood is non-rot-resistant)
• Soil mix: 60% topsoil, 30% compost, 10% potting soil
• Tools: Circular saw or hand saw, drill, driver bits, tape measure, level, shovel, spading fork, staple gun
• Safety gear: Gloves and eye protection

The 4-by-6-foot planter box built by Lowe’s uses 2×8 cedar side boards and 2×4 corner posts. Look for our recommendations on pre-sized kits and materials at top-rated above ground planter options if you prefer a kit over building from scratch.

Dimensions That Actually Work For Gardening

A planter box needs the right proportions to grow vegetables well. Go too shallow and tomatoes can’t root; go too wide and you cannot reach the center.

• Depth: 16 to 18 inches for most vegetables (tomatoes, peppers, cucumbers); 12 inches minimum for shallow-root crops
• Width: 4 feet or less — anything wider forces you to step into the bed and compact the soil
• Length: 4 by 6 feet is the standard size that fits most backyards and handles a good variety of plants
• Board thickness: A 2-inch board typically measures 1¾ inches thick — mark your framing lines after checking the real measurement

How To Build An Above Ground Planter Box: Step By Step

The assembly follows a logical order: cut, frame, bottom, position, fill. Each step builds on the last, so read through once before picking up a tool.

Step 1: Pick The Site And Call 811

Choose a south-facing spot that gets 6 to 8 hours of direct sunlight daily. Call 811 at least two days before digging to have underground utilities marked. That free service prevents you from hitting gas or power lines.

Step 2: Cut Your Lumber To Size

For a 4-by-6-foot box using 2×8 boards, cut two walls at 7 feet and two walls at 4 feet. Cut four corner posts from 4×4 or doubled-up 2×4 lumber to match the wall height. If you use 2x4s for the posts, cut them to the exact height of the bed.

Step 3: Assemble The Frame

Clamp a long wall board flush with a corner post. Drill pilot holes through the post into the board, then drive 3-inch screws. Repeat for each side. Keep the posts on the inside of the frame — this gives a clean exterior look and better structural support.

The frame will stand square on its own once all four sides are screwed to the corner posts. Check with a tape measure — opposite sides should match within ¼ inch.

Step 4: Attach The Bottom Mesh

Staple hardware cloth or chicken wire across the entire bottom of the frame using 5/16-inch staples. Space the staples every 6 inches. The wire stops burrowing animals from coming up through the bed while letting water drain freely.

Step 5: Line The Interior (If Needed)

Staple landscape fabric or heavy-duty plastic along the interior walls only if you used non-rot-resistant lumber. Do not line the bottom — the plastic will trap water and rot roots. Cedar does not need a liner at all.

Step 6: Position The Box On Level Ground

Set the frame in place. Outline it with a shovel, remove the grass inside, and loosen the native soil with a spading fork. Filling without loosening the ground underneath creates a perched water table that drowns roots. Make sure the box sits level — a tilted bed drains unevenly.

Step 7: Fill And Plant

Mix the soil components together — a tarp makes mixing easy. Fill the bed to within an inch of the top. The soil will settle several inches over the first few weeks. Plant container vegetables by making a hole, loosening the root ball, and filling back lightly. Water immediately after planting.

Common Mistakes That Ruin A Planter Box

The shortcuts people take are the same every year, and each one costs you a season of growth.

• Using non-porous plastic as a liner: It blocks drainage and kills beneficial worms. Use landscape fabric or skip the liner entirely with cedar.
• Building wider than 4 feet: You will trample the soil trying to reach the center, which compacts the roots and reduces yield.
• Skipping the hardware cloth: Voles and gophers will find your bed within weeks and hollow out the root zone from below.
• Filling on unloosened ground: The soil layer stays shallow, and deep-root plants like tomatoes cannot extend their roots into the native earth.
• Ignoring the 16-inch depth rule: A 12-inch bed can grow lettuce and herbs, but it strangles peppers, cucumbers, and tomatoes.

Cost Breakdown For A Standard 4×6 Box

Building a raised planter box does not require a big budget. The $100 estimate from Gardenary covers basic lumber and hardware if you build the simplest rectangular box without legs or fancy joinery.

Cedar costs roughly double what pine does, but it lasts 8 to 12 years untreated versus 3 to 4 years for unlined pine. The extra upfront cost pays for itself if you plan to keep gardening.

The Hidden Drainage Method

FixThisBuildThat outlines an alternative construction for an elevated planter box on legs. The key difference: you build leg assemblies, create a lower shelf, install a solid bottom with drainage gaps, and then add the liner. This works best for deck or patio installations where you cannot set the box directly on the ground. The leg method also eliminates the need to loosen native soil, because the entire growing volume sits above the surface.

Planter Box Checklist

Use this list before you head to the lumber yard so nothing gets missed:

• Sunny south-facing site measured and marked
• Utilities marked (call 811)
• Lumber, screws, hardware cloth, and liner purchased
• Gloves and eye protection packed
• Soil components ordered or sourced (topsoil, compost, potting soil)