How to Build a Raised Garden Bed

A DIY project for a permanent garden box to provide a raised bed for your plants and decorate your backyard.

October 2017

By Sara Bendrick

For those who want to improve their backyards, author Sara Bendrick provides a variety of DIY projects in Big Impact Landscaping so homeowners can get the most out of their property, expand their living space, and enjoy more time outdoors. Here, Bendrick gives step-by-step instructions for building a permanent U-shaped vegetable garden box — as well as an attached bench to help you enjoy your backyard plants.

Photo by Joe Dodd

U-Shaped Vegetable Garden

Level: Beginner to intermediate

Cost: $$

Time commitment: 1 day

Professionals needed: None

Dimensions: 8-feet-by-9-feet U-shape

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Garden beds make any yard come alive, and the best part about having a raised bed is that it looks attractive even in the off-season because it defines and organizes the space in the yard. A simple U-shaped bed gives you maximum growing space with all-around access. Adding a cute little bench to the cap and some decorative diamonds can really dress it up! This large garden can be a focal piece or complement other features in the yard. Plan to hand water unless you want to install an irrigation system (I prefer drip).

Drawing by Sara Bendrick

Tools

• 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)

Materials

• Three 2-inch-by-12-inch-by-10-foot boards, two cut into 9 feet and one cut into two 51-inch pieces

• Two 4-inch-by-4-inch-by-8-foot redwood boards, cut into eight 22-inch pieces

• Eight 2-inch-by-12-inch-by-8-foot boards

• Four whole

• Four cut to 5-feet-6-inches

• Six 2-inch-by-4-inch-by-10-foot boards (wait and cut based on your actual dimensions in case they vary a little) (cap)

• Two 2-inch-by-4-inch-by-8-foot boards, each miter cut to make twelve 15-inch pieces (diamonds)

• One 2-inch-by-6-inch-by-10-foot, cut to two 51-inch boards (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

• One 1-pound box of 2-1/2-inch deck screws

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Photo by Joe Dodd

Step 1: Select your location: Pick a nice sunny area that is fairly level and easy to get to.

This garden box will fit in a 9-by-9-foot space; you can adjust yours to be bigger or smaller depending on your area. However, I don’t recommend going smaller than 30 inches (2-1/2; feet) for the arms, as it gets too tight to plant two rows of veggies.

Photo by Joe Dodd

Step 2: Select and cut your lumber: I used “merch” redwood, which is really rough and imperfect redwood, as it drops the price significantly and works great for a rough, rustic veggie bed. I recommend using 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.

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Step 3: Grade your level: Most sites are going to need some slight leveling or be cut and filled to get an even surface. You have two options: dig out the high areas and transfer the soil to the low areas or build up the whole space with the 3/4-inch gravel. Compact it with a hand tamper and use a rake to level it out.

Photo by Shutterstock

Step 4: Start with the back: Since we are placing this planter against a fence, start with the long back pieces by assembling them on the ground. To do this, take one 9-foot board and line it up with one of the 22-inch, 4-by-4 posts. The bottoms should line up square and overhang the side by 1-3/4 inches or by the width of your lumber, as a sidepiece will fit in there later. Use two 3-1/2-inch lag bolts and washers to attach about 2-1/2 inches down from each edge so that they are roughly in the center of the 4-by-4. Predrill holes as shown in step 5 and secure as shown in step 6. 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, still leaving a 1-3/4-inch gap on the end.

Now take an 8-foot 2-by-12-inch board and slide it in to match the bottom board height and into the overhanging space. Secure with the same bolt and washers as described above and repeat on the other side.

Photo by Joe Dodd

Step 5: Predrill the holes: Use a 3/8-inch drill bit to predrill your lumber as you go before inserting screws, which will help prevent splitting and will guide your lag bolt into the lumber.

Photo by Joe Dodd

Step 6: Secure 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. Lag bolts are heavy-duty screws that are best for securing thick lumber.

Photo by Joe Dodd

Step 7: Run a string line and add the sides: Prop up the back and make sure that it is sitting level. Secure a string line to the back and pull the line so that it is perfectly perpendicular, using a speed square to check that it is 90 degrees. Secure it to another structure or tie it to a stake in the ground. Take one of your 8-foot boards and slide it into the 1-3/4-inch overhanging edge, referencing the string line, and secure with lag bolts.

Photo by Joe Dodd

Step 8: Attach the front: Using a clamp or an extra pair of hands, attach a 30-inch 4-by-4 front piece to one of the sides. Clamps are great if you need to force a warped board into place.

Photo by Joe Dodd

Step 9: Check your level: Use a level to verify that you’re building straight up and then attach the 30-inch piece to the 4-by-4 post with bolts.

Photo by Joe Dodd

Step 10: Add the top layer of wood: Drop in the top side pieces, predrill and secure with bolts, as you did in steps 5 and 6, except this time you’re building in place. The top layer will sit a few inches taller than the 4-by-4, so that when you fill with soil you can cover the top of the 4-by-4 to make it disappear.

Photo by Joe Dodd

Step 11: Finish the box: Continue building the box by finishing the “legs,” or the 8-foot sides, the 30-inch front and the 5-foot-6-inch inner side on both sides of the planter. Your 4-by-4 posts on the inner part of the planter should sit flush with the end of the 5-foot-6-inch boards. Then take the 51-inch 2-by-12 boards and attach them to the 4-by-4 posts, closing the box so that you have a U-shape.

Photo by Joe Dodd

Step 12: Add gravel and dirt: Add a 2-inch layer of gravel to the bottom to help with drainage. Then fill the box up with 3-1/2; cubic yards of garden soil. After filling the box a few inches deep, use a hose to mist the soil down to help compact it and make it moist for your new plants, and use a rake to spread it around. Repeat this step until the container is filled to about 2 inches below the lip and the soil just covers the 4-by-4 inside posts. For this amount of soil it’s probably easiest to get it delivered in bulk from a landscape supply store, or you can buy it in bags, but it will be more expensive that way.

Photo by Joe Dodd

Step 13: Add a cap and bench seat: Secure your two 2-by-6-by-51-inch boards on the inside corner of the bench, spacing them 1/2-inch apart. Then take your 10-foot 2-by-4-inch boards and line up a board so that it is flush with the inside edge of the top vertical 2-by-12-inch boards. This will leave an overhang on the outside by about 1-1/2 inches. Make miter cuts on a miter saw to get nice, clean 45-degree angles where the boards overlap in the corners. Use a drill and 2-1/2-inch exterior screws to secure the cap in each corner and about every 12 inches along the long sides and about every 6 feet on the short 30-inch pieces.

Photo by Joe Dodd

Step 14: Add a decorative backdrop: Use two 8-foot 2-by-4-inch boards and miter cut 12 at 15 inches long to make three separate diamonds. Using 4 pieces per diamond, attach by using a 2-1/2-inch exterior screw on the side. Measure out from the center of the planter and mark 18 inches above on the fence; attach your center diamond using exterior deck screws or a finish nail gun. Space out the other two diamonds about 12 inches away on both sides and secure the same way. Now get planting!

Photo by Joe Dodd

Modern Concrete and Wood Bench

This simple, modern bench is a functional piece but also drives a strong modern design style throughout the yard. The concrete corners were formed and poured all at once with a gray-colored concrete patio. We built them 18 inches tall and left 4-inch-deep by 11-inch by 6-inch notches for the 4-by-4-inch cedar planks to sit inside. Using a painted angle iron brace attached with redheads to the concrete and with screws to the wood, we were able to secure each of the planks 1/2-inch apart so that no hardware is visible from the top. While simple in theory, getting everything lined up just right is the key to a perfect modern bench. Placing decorative pea gravel raised the ground level so that the benches sat at a standard 16 inches tall. Finishing the space off with a matching lumber coffee table creates a modern and functional entertaining area that ties in perfectly with the other elements of the yard.

Reprinted with permission from Big Impact Landscaping by Sara Bendrick and published by Page Street Publishing, 2017.