DIY Cedar Raised Garden Bed

Spring is the perfect time to build raised garden beds. March in the mid-Atlantic is the ideal time to plant cool weather crops such as spinach, lettuce, carrots, potatoes, peas, and radishes. Some even plant onions and garlic. Raised garden beds offer countless benefits to gardening, specifically ease of gardening and better weed control. 

Not a carpenter? Not a problem. I'll walk you through this step by step.

In this article:

1. Materials list for 4ftx8ftx16in cedar raised bed

2. Step-by-step construction instructions with photos

3. How to create excellent raised bed soil 

Materials List

There are numerous types of lumber, but cedar, while more expensive, will last at least 10 years. Avoid chemically treated woods such as pressure-treated or railroad ties. For each 4ftx8ftx16in garden bed, you will need:

• 2inx8inx8ft cedar boards (“side”); Qty: 4
• 2inx8inx4ft cedar boards (“end”); Qty: 4
• 4inx4inx2ft cedar posts (“corner”); Qty: 4
• 2inx2inx2ft cedar boards (“support”); Qty: 2
• Coated deck screws with star head, 3.5-inch; Qty: 56 (1-lb box = approx. 57 screws)
• Coated deck screws with star head, 2.5-inch; Qty: 8
• Cardboard or newspaper (enough to cover bottom of bed once assembled)
• Miscellaneous tools: Drill with star bit and auger (optional), level, large clamp, tape measure, pencil, chalk, square, shovel, post hole digger, hand shovel, small saw (if roots are encountered).

 

HOW TO BUILD A RAISED GARDEN BED

Assemble the 4-foot garden bed ends

1.) Draw a straight line, 4 feet long, on a level surface. Place the top end of each 24-inch 4x4 post along the line, 4 feet apart. Square posts to the line ensuring that they remain parallel to each other.

 

2.) Place a 4-foot 2x8 section of wood on top of the 4x4 posts, being careful not to disturb the alignment. Adjust the 4x4s to keep them square to the line, and parallel. Using 3-inch deck screws, fasten the side board to the right post with three 3-inch screws; repeat on left. See photo in step 3 for spacing of screws. 

3.) Place the second 4-foot end piece under the other and fasten in the same manner ensuring boards remain square.  

4.) Move completed end piece aside and repeat steps to build opposing 4-foot end.

Assemble the 8-foot garden bed sides

1.) To assemble the 8-foot side boards to the garden bed ends, draw a straight line 4 feet long and place a completed 4-foot end section on the line, flat side flush with the ground, end boards facing out. Place a square on the corner of four-foot end section and run a tape measure down length of square. Place opposing four-foot end section at approximately 8 feet, end boards facing out.

2.) Square up the sections by measuring each end at about 8 feet. Measure diagonally to ensure that the base of the bed is square. Next, spread out the 8-foot side boards and try to match up two that are approximately the same length. Unless you cut them perfectly yourself, there will always be slight differences. Remove the square and place an 8-foot side board along the sides, adjusting the ends to fit.

3.) Drop eight 3½-inch screws near each corner of the garden bed. Fasten a clamp to hold one 8-foot side board to the 4-foot end piece, evening up the edges. 

4.) Using the photo below as a guide, screw four 3½-inch screws in to anchor the 8-foot side board to the 4-foot end piece and the 4x4 post, centering screws on each.

You may have to alter the boards somewhat to avoid screwing into knots. Countersink the screws slightly. Repeat the process for the other three corners.

5.) Stack the second 8-foot side board on top of the first board that is already anchored and adjust to even up the seams as best as possible. Repeat the screw pattern to anchor the second 8-foot side board.

6.) Repeat the process to attach the remaining 8-foot side boards to the other side.

Assemble the side support pieces

1.) Mark the halfway point of each of the 8-foot sides with a pencil. Place one 2x2x24-inch support piece on the inside of the garden bed at the halfway mark. Drill four 2 ½-inch screws into the 2x2 support, anchoring it to the 8-foot side of the garden bed. 

2.) Repeat on other side.  

Final Placement

1.) Pick a sunny location for the garden bed. It is time to “bury” the bed.

2.) Using a shovel, or spray paint, mark the location of each corner and support post. Using a post hole digger, dig down approx. 8 inches for each post. Toss the dirt to the inside of the bed. Place the garden bed down into the freshly dug holes. 

3.) Using a small hand shovel, shift the dirt so the the bed will be level. 

 

Garden bed construction is now complete. Whew. Sit back and take a load off! Enjoy the beauty.

How to Create Excellent Raised Bed Soil

Once you’re sufficiently hydrated, the fun begins. Filling the beds with DIRT! 

For each 4x8 bed you will need:

• Potting soil                                             Qty: 2 lg bags
• Topsoil, bagged                                      Qty: 8 cu.ft.
• Peatmoss, bagged                                  Qty: 6 cu.ft.
• Compost or dried manure                       Qty: 6 cu.ft.
• Shredded leaves, if available                   Qty: 2-inch layer

Line the bottom of the garden bed with cardboard or newspaper. Add dirt and amend the soil with potting soil, peatmoss, compost, and shredded leaves, mixing each as it is added. Leave 4-inch headroom at the top of the garden bed to allow for mixing.

Alternatively you could use the hugelkultur method, in which you first put down a layer of decaying logs and sticks. This has many benefits, which Melissa wrote about in this article.

Plant. Water. Watch. Grow. Eat. Enjoy! 

(Due to their nature, raised beds will require more watering than traditional gardens. A light layer of straw in the summer may help preserve moisture. Soaker hoses are a great investment too.)

Making your own garden beds can be one of the most satisfying things you’ll ever do. Easy enough to complete in an afternoon, yet sturdy enough to give years of enjoyment.