How to Build a Raised Bed Garden

Use these step-by-step instructions to construct an attractive garden box with an attached bench, perfect for vegetables, herbs, or cut flowers.

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by Joe Dodd

Garden beds can make any yard come alive. The best part about having a raised bed is that it looks attractive even in the offseason, because it defines and organizes the space in the yard. A simple U-shaped bed offers maximum growing space with all-around access. Adding a little bench to the cap can really dress it up. This 8-by-9-foot U-shaped raised bed can be a focal piece or complement other features in the yard. Plan to hand-water unless you want to install an irrigation system.

Before You Build

Select your location. Pick a sunny area that’s fairly level and easy to get to. These instructions will create a garden box that fits a 9-by-9-foot space and is designed to be placed against a fence; you can adjust yours to be bigger or smaller depending on your area. However, don’t go smaller than 30 inches in width for the arms, as it will get too tight to plant two rows of veggies.

Select and cut your lumber. I used “merch” redwood, which is rough and imperfect, because it lowers the price significantly and works great for a rough, rustic veggie bed. Use raw redwood or cedar for planters. Never use pressure-treated lumber for a vegetable garden. With a miter saw, cut all your lumber to the specified dimensions above, or adjust for your own space.

Grade your site. Most sites will need some slight leveling to get an even building surface. You have two options: Dig out the high areas and transfer the soil to the low areas, or build up the entire space with 3/4-inch gravel. Compact it with a hand tamper, and use a rake to level it out.

Plant Palette

Tools and Materials

  • Measuring tape
  • Pencil
  • Miter saw or circular saw
  • 2- to 3-inch level
  • Shovel
  • Rake
  • Hand tamper
  • Impact driver or drill and socket bit
  • String line
  • Speed square
  • Stakes
  • Clamps
  • Hose with multispray nozzle
  • Finish nail gun (optional, if not using deck screws)
  • Three 10-foot-long 2-by-12-inch boards, cut into two 9-foot lengths and two 51-inch lengths
  • Two 8-foot-long 4-by-4-inch redwood posts, cut into eight 22-inch lengths
  • Eight 8-foot-long 2-by-12-inch boards, 4 cut into 5-1/2-foot and 2-1/2-foot lengths, and 4 left whole
  • Six 10-foot-long 2-by-4-inch boards, cut to length after main construction (for caps)
  • Two 8-foot-long 2-by-4-inch boards, miter-cut into twelve 15-inch lengths (for decorative diamond backdrop)
  • One 10-foot-long 2-by-6-inch board, cut into two 51-inch lengths (for bench)
  • 1/3 cubic yard of 3/4-inch gravel
  • Thirty-two 3-1/2-inch-by-3/8-inch lag bolts and washers
  • 3/8-inch drill bit
  • 3-1/2 cubic yards of garden soil
  • 1-pound box of 2-1/2-inch deck screws

Construct the Raised Bed

Make the building process smoother by pre-drilling your holes: Use a 3/8-inch drill bit to pre-drill your lumber before inserting screws, which will help prevent splitting and will guide your lag bolt (a heavy-duty screw ideal for securing thick lumber) into the lumber. Use a socket bit with an impact driver to secure the two pieces of lumber together with lag bolts and washers on each end.

1. Start with the back. Because we placed our planter against a fence, we assembled the long back pieces on the ground. To do this, take one 9-foot board and line up the bottom edge with the base of one of the 22-inch 4-by-4 posts. The 9-foot board should overhang the side of the post by 1-3/4 inches, or by the width of your lumber, as a side piece will butt against the overlap later. Drill holes for two lag bolts, centered on the 4-by-4 and about 2-1/2 inches in from the long edges of the 9-foot board. Use two 3-1/2-inch lag bolts and washers to attach the board and post together. Attach a second 9-foot board above the first in the same manner, and then attach a second 22-inch 4-by-4 post on the other side, remembering to create a 1-3/4-inch overlap on the end.

2. Add the sides. Prop up the back and make sure it’s sitting level. Secure a string line to one corner and pull the line so it’s perfectly perpendicular, using a speed square to check the angle. Secure the string line to another structure or tie it to a stake in the ground. Take one of the 8-foot boards and slide it into place against the outside of the back post, butting it against the overhanging edge of the back boards. Check the angle of the board against the string line, and secure it with lag bolts and washers as described above. Move the string line to the other back corner and repeat the process.

3. Attach the front posts. Use a clamp or an extra pair of hands to place another 4-by-4 post against the inside of one of the side pieces, aligning the end of the side board with the frontmost face of the post. Clamps are great if you need to force a warped board into place. Use a level to verify that you’re building straight up, and then attach the side board to the post with lag bolts and washers.

4. Construct the inner sides. Attach one of the 5-1/2-foot boards to a 4-by-4 post, again aligning the end of the board to the face of the post. Repeat with another 5-1/2-foot board and 4-by-4 post.

5. Attach the front boards. Stand one of the inner side pieces so that the end with the post attached is at the front of the raised bed, with the post on the inside of a leg of the U. Use clamps or extra hands to place a 2-1/2-foot board against the front of the outer and inner side pieces, aligning the ends of the board with the outermost sides of the side boards (the side board ends should now butt against the front board). Use a level and a speed square to check that both corners are square and upright before drilling and attaching the front piece with lag bolts and washers. Repeat on the other leg of the U. You’ll still be missing the final piece to complete the box; leave it aside for the moment.

6. Add the top boards. Slide in the second set of 9-foot side pieces, pre-drill, and secure with lag bolts and washers. The tops of these boards will sit a few inches taller than the 4-by-4 posts, so you can cover the tops of the posts with soil to hide them. Continue adding boards around the box, following the order of the initial construction.

7. Finish the box. Attach the remaining 4-by-4 posts flush against the ends of the inner side boards, on facing sides. Then, attach the 51-inch 2-by-12 boards to the 4-by-4 posts, closing the box with the final pair of posts on the outside of the enclosed U-shape.

8. Add gravel and dirt. Add a 2-inch layer of gravel to the bottom to help with drainage. Then, fill the box with 3-1/2 cubic yards of garden soil. While you can buy enough bagged soil to fill this raised bed, it will be much less expensive – and much less work – to get it delivered in bulk from a landscape supply store. Use a hose to mist the soil after every few inches of fill to settle it and make it moist for your new plants, and use a rake to spread the soil around. Continue until the container is filled to about 2 inches below the lip and the soil just covers the 4-by-4 inside posts.

9. Add the bench seat. Secure the two 51-inch 2-by-6 boards on the inside of the U-shape, spacing them 1/2 inch apart to create a bench.

10. Add the cap boards. Butt the end of one of the uncut 10-foot 2-by-4-inch boards against the bench, and align the inner edge with the inside edge of the raised bed frame. This will leave an overhang on the outside of about 1-1/2 inches. Mark the corner, and make a miter cut to get a clean, 45-degree angle where the cap boards will meet. Use a drill and 2-1/2-inch exterior screws to secure the first cap board in each corner and about every 12 inches along the length, and then align the mitered edges and mark the next corner to cut. Continue marking, cutting, and attaching the cap boards around the raised bed, anchoring each one at the corners and about every 12 inches on the long sides, or 6 inches on the short 30-inch pieces.

11. Add a decorative backdrop. Use the twelve 15-inch 2-by-4s to make three square frames, which you’ll rotate on their points to make a diamond pattern. Anchor each corner with a 2-1/2-inch exterior screw driven straight into the side of one piece. Measure 18 inches above the center of the planter on the fence; attach the first frame at this mark using exterior deck screws or a finish nail gun. Space the other two frames about 12 inches away on both sides and secure the same way. Finally, get planting!

Sara Bendrick is a designer and TV host for the DIY Network. This project is reprinted with permission from her book Big Impact Landscaping, published by Page Street Publishing.