Build a raised garden bed with macrocarpa sleepers

Build a raised garden bed with macrocarpa sleepers
Raised garden beds look great and they allow you to garden at a comfortable height. They have many other benefits, including better drainage for winter growing, thermal insulation to help plants grow and a tidier garden layout.

 The Build

Building a raised garden bed is easy to do. Choose a level, sunny spot out of the wind to site your bed. Rectangular beds work best as it can be hard to access the centre of a large square garden bed.

Macrocarpa SleepersTrustwood Sleepers

Visit your local Central Landscapes yard and choose from our range of sleepers. Get your sleepers delivered or grab one of our free loan trailers to bring them home.

Here, we're putting together a rectangular garden bed using 200mm by 100mm macrocarpa sleepers: 2.1 metres for the long side, and 700mm lengths for the short side. We're stacking them vertically so we get a 400mm high structure, which is a good depth for plant roots to develop.

This garden bed is on a concrete base, so we'll elevate it off the ground with pavers to prevent rot.

Macrocarpa Sleepers

Macrocarpa is untreated hardwood, so the sleepers should not be placed directly onto wet soil. If you're planning to build your raised garden bed on a lawn area or bare ground, lay a base of Gap 7 beneath the sleepers first.

Macrocarpa Sleepers

If you're not planning to build immediately, store your sleepers off ground, to keep the timber dry.

Cutting macrocarpa sleeper
You may need to trim your sleepers so they're all the correct length. 
Measure before cuttingMark two points
Mark two points (each 50mm in from each side) at both ends of your 700mm short side sleepers.
Drill holes
Drill two 10mm deep countersink holes with a 32mm spade bit. These will allow your coach screws to sit flush with the surface.
Drilling a hole in Macrocarpa sleeper
Drill 12mm holes through the sleeper for the 10mm coach screws.
position correctly
Position your sleepers where you want them; use small pavers as foundation blocks to keep the sleepers off the concrete. This will also allow the garden bed to drain properly, avoiding water-logging.
Square the sleepers
Make sure the sleepers are square and level.
We're using 150mm M10 galvanised coach screws (with washers). You can also use stainless steel screws for maximum durability.
Push the screws in
Push the screws through the 12mm drilled holes and tap with a hammer to make a drill mark in the adjoining long side sleeper.
Drill pilot holes
Remove the short side sleeper and drill 6mm pilot holes.
Screws with wax
Rub wax onto the thread of your coach screws. This will make it easier to screw them in.
Installing coach screws with Racket driver 
Install the coach screws (including washer) with a racket driver. Partially screw one on each side and tighten them alternately to ensure the sleepers draw together evenly.
Repeating the process
Once the base layer is complete - repeat the process with the second layer.
Stainless steel multigrips
Fix the two layers together in the corners using stainless steel multigrips.
Now we've completed the raised garden box, we can start filling it!
Raised garden bed broken concrete base
In this case, we're recycling broken concrete as a base. Scoria also works well as a free-draining base layer. Next, we'll staple a lining material to the inside of the box, to provide a water barrier between the sleepers and the soil. You can use polythene plastic or even canvas.
Living Earth Garden Mix
Once the lining is in place, fill the bed with topsoil and then top up with Living Earth Garden Mix or Veggie Mix. Now you're ready to plant!
Raised garden bed