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Difficulty: Intermediate
A decorative raised garden bed is a great way to enliven your backyard and grow plants in style.
Here is a step-by-step guide to building a raised garden bed with seating. It is built from cost-effective timber but gives the look of more expensive masonry by using blueboard and textured paint. You can use the provided measurements or adjust them to suit your space and needs.
As this project involves power tools, please follow all safety guidelines provided by manufacturers and use the recommended protective gear.
Let us know if you have any questions. We’d be happy to assist.
Video Tutorial
Steps
Step 1
Mark out the raised garden bed.
Determine the exact location and size of your bed. My bed measures 2400 x 1200 x 400mm.
Leave approximately 50 to 100mm in front of the bed. Clear the area behind.
Now mark out the bed using a straight edge and spray and mark paint. You can use a carpenter's square to align your straight edge at 90 degrees for the sides. Don’t forget to mark the corners and spacings for posts at the ends and sides of the bed.
Bed lengths measuring more that 1200mm should also have a centre post added. I inserted a centre post at the 1200mm mark.
Dig post holes, including the centre hole. For a 400mm high bed, the post hole should measure at least 200mm in depth. The side walls work to tie the structure together so deeper post holes are not required.
Step 2
Position the bed's front row in place.
Secure the 200mm x 75mm x 2.4m treated Pine sleeper to your worktable. Measure 500mm from one end and mark it. Use a circular saw to cut along this point. Don’t forget to wear personal protective equipment (PPE) while cutting, including gloves, safety glasses and a dust mask.
Now place the 200mm x 50mm x 2.4m treated Pine sleeper horizontally along the front line marked on the ground as in Step 1. Level it using a spirit level. Use the 500mm cut length as a temporary vertical support to hold the 2.4m sleeper in place. You can clamp the 500mm length to the sleeper.
Step 3
Construct bed posts.
Determine the height of your bed posts by measuring the bottom of the centre post hole dug in Step 1 to the top of the 2.4m sleeper placed at the front of the bed in Step 2. Add 200mm to this measurement if your bed has a two sleeper (400mm) high wall.
Cut a section of the 200mm x 75mm x 2.4mm sleeper according to this height using a circular saw. You should now have your first post. Repeat this process to build posts for your bed's sides and ends.
Step 4
Secure posts to the bed.
Position one post in the centre post hole. Make sure that the horizontal 2.4m front sleeper is level and that the post is completely straight or plumb. Clamp the post to the sleeper and then use a drill driver and 100mm screws to secure the two together.
Now add concrete and water to the post hole. Refer to the product label for instructions on how to mix concrete. Don’t forget to double check that the post is plumb and the front sleeper is level.
Repeat this process to add posts to the ends and sides.
Step 5
Add side sections and second front row.
Repeat the process described in Step 2 to add sleepers to the sides of the bed.
You can then add the second horizontal row of 200mm x 50mm x 2.4m treated Pine sleeper on top of the first by using 100mm screws.
Step 6
Cap the front and sides of the bed.
Lay a 200mm x 50mm sleeper down flat on top of the front horizontal rows of sleepers. Position it so that there is an overhang of at least 20mm in front of the post faces. Use a combination square to align it correctly and evenly.
Secure the top sleeper to the posts and the front horizontal sleeper row using 100mm construction screws.
Repeat this process when applying a top sleeper along the sides of the bed. You may need to cut the top side sleepers according to your bed’s width. My top side sleepers measured 1145mm.
Step 7
Cut and paint blueboard.
Cut blueboard according to the size of your raised garden bed. Determine the height of your bed by measuring the distance from underneath the top capped sleeper to the bottom of the front horizontal sleeper. In my case it was 400mm. Next, measure the front and sides of your bed.
Mark out these dimensions on your blueboard and cut accordingly. Note that blueboard should only be cut using a score and snap knife.
Paint the face side of your cut sections using exterior grade texture paint and allow to dry. The textured paint will give the blueboard a look similar to rendered concrete.
Step 8
Add decking to the capped front section.
Cut three pieces of decking measuring 2500mm in length using a circular saw. Place one piece at the front of the top sleeper. Position it so that there is an overhang of 35mm in front of the sleeper face and an overhang of 50mm on each side. Use a combination square to align it correctly and evenly.
Clamp the decking in place, countersink and secure it to the top sleeper using 50mm screws.
Repeat the process to add two more decking slats behind the first. Ensure they are evenly aligned.
Step 9
Add decking to the capped sides.
With your combination square at the 45 degrees position, mark a line from the inside to the outside corners of the top front sleeper decking. Now set your power saw depth to the thickness of the decking and cut along the marked line. Repeat for the other end.
To add decking to the sides, measure and cut three pieces of decking according to your bed’s width. Make 45 degree cuts on one end and square ends to the other. Clamp them in place and secure to the front decking and side top sleepers using 50mm screws.
Step 10
Secure blueboard to the bed.
Apply a generous amount of construction adhesive to all post faces. For larger beds, add some additional blocks of sleeper offcuts if needed. Screw these onto the sleeper rows. Make sure they are evenly spaced between posts to keep the blueboard rigid.
Position your cut and painted front blueboard section from Step 6 on the front face of the bed. Press it firmly into the adhesive. This should hold the blueboard in place as you drive in the screws.
Pre-drill, countersink and secure the blueboard with 50mm screws. Repeat this process to secure blueboard to the bed sides.
Step 11
Fit decking beneath the capped sections of the bed.
Measure lengths of decking to fit on the front and sides of the bed and flush with the bottom of the capped decking installed above. Cut the decking according to these measurements.
Position flush with the capped decking and secure with 50mm screws. Do this for the front and sides of the bed.
Step 12
Conceal corner joins.
Measure the distance between the top and bottom of the front blueboard corners on the bed. Cut sections of aluminium angle to suit and secure with construction adhesive, concealing the corner joins.
Use an exterior filler to cover the screw heads in the blueboard and touch up the paint once dry.
Step 13
Add plants and final touches.
Fill the bed with soil and then add your preferred plants. I used a native lemon-scented myrtle as a central feature and surrounded it with pink cordylines.
Now apply decking oil to the decking boards. Finally, add mulch and water well. Your decorative raised garden bed is now finished.
Materials
- Seven 200 x 75mm 2.4m treated Pine sleepers
- Two 200 x 50mm 2.4m treated Pine sleepers
- Concrete
- Eight 90 x 22mm 3m treated Pine decking
- 100mm construction screws
- 150mm construction screws
- 30 x 30 x 1.5mm aluminium angle
- 2440 x 1200 x 7.5mm blueboard
- 50mm exterior screws
- Construction adhesive
- Spray and mark spray paint
- Decking oil
- Exterior grade texture paint
- Exterior filler
- Soil
- Mulch
- Plants.
Tools
- Tape measure
- Ruler
- Pencil
- Carpenter's square
- Combination square
- Straight edge
- Short and long spirit levels
- Digging tools (e.g. spade)
- Wheelbarrow
- Circular saw
- Drill driver
- Counter-sinking bit
- Paintbrush and tray
- Hacksaw or angle-grinder with metal cutting blades
- Score and snap knife
- Safety gear.
Images
