How to Build a Custom Cedar Raised Garden Bed from Scratch
By Greenes Fence Company: Cedar Raised Garden Beds ... | Published: 2026-10-25
Category: How-to Guides
Learn to build a custom cedar raised garden bed from scratch using boards and posts. This guide covers planning, assembly, and common pitfalls.
Quick answer
To build a custom cedar raised garden bed from scratch, plan your dimensions, gather untreated cedar boards and posts, assemble the frame with dovetail connectors, and secure it on level ground.
Why build from scratch instead of using a kit?
Building from scratch gives you total control over the size, shape, and height of your raised bed. You can match odd garden spaces, add extra depth for root crops, or create a tiered layout. The trade-off is that you need to measure and cut carefully, and you may need more hardware than a pre-packaged kit provides.
Choosing the right cedar components
Cedar is naturally rot-resistant and safe for edible gardens. For the walls, use boards like the Original Cedar Board 15 in x 3.5 in RCB15, which is 15 inches long and 3.5 inches tall. For corner posts, the Premium Cedar Tall Post 11 in x 2.5 in x 2.5 in RCT lets you stack multiple layers to increase bed height. If you want a solid floor, the Cedar Dovetail Bottom Board 10 in. x 3 7/16 in. RCPBDB103 works as a base or as shorter side panels.
Step-by-step assembly guide
- Plan your bed dimensions and layout: Measure your garden space and decide on length, width, and height. For a standard 4x8 bed, you'll need eight 15-inch boards per side (32 total) and four tall posts. Mark the ground with stakes and string. Double-check that your bed fits in the space and allows at least 18 inches of walking room around it.
- Cut and prepare your cedar boards: Using a miter saw or handsaw, cut the cedar boards to your desired lengths. Sand any rough edges to prevent splinters. If you want a floor, cut the dovetail bottom boards to fit the base. Wear a dust mask when cutting cedar; the fine dust can irritate your lungs.
- Assemble the first layer of walls: Insert the cut boards into the slots of the corner posts. For a tall post, the slots hold three boards vertically. Start with the bottom board, then add the middle and top boards, ensuring they are flush. Tap boards gently with a rubber mallet if they are snug; avoid splitting the wood by forcing them.
- Add additional layers for height: Stack another set of tall posts on top of the first set, aligning the slots. Insert the next layer of boards. Repeat until you reach your desired height. Each tall post adds 10.5 inches of height. Check that the posts are aligned vertically; a shifted post will make the bed crooked.
- Secure the bed and add a floor (optional): Place the assembled frame on level ground. If using a floor, slide the dovetail bottom boards into the bottom slots before placing the frame. Use landscape fabric or hardware cloth underneath to block weeds and burrowing pests. Level the bed with a carpenter's level; an uneven bed can cause soil to shift and stress the joints.
Key cedar components for your custom bed
- Original Cedar Board 15 in x 3.5 in RCB15: The 15-inch cedar board is the shortest board available for cedar raised garden kits, measuring 11/16" wide by 3.5" high by 15" long. Use this board for narrow beds or to fill small gaps in a custom layout without needing to cut longer boards.
Original Cedar Board 15 in x 3.5 in RCB15 - Premium Cedar Tall Post 11 in x 2.5 in x 2.5 in RCT: The tall post holds three 3.5-inch tall boards high, adding 10.5 inches of height per layer, and can stack on top of short posts. Stacking tall posts lets you build deep beds for root vegetables or to make gardening easier on your back.
Premium Cedar Tall Post 11 in x 2.5 in x 2.5 in RCT - Cedar Dovetail Bottom Board 10 in. x 3 7/16 in. RCPBDB103: This dovetail bottom board is used as the floor of the planter box or as shorter side panels, made from untreated cedar that can be left natural or stained. Adding a floor helps control weeds and pests, and the dovetail design locks boards together for a sturdy structure.
